Greek does something most European languages do not: it skips the sun, moon, and old gods entirely when naming the days of the week. Where English keeps a trace of Norse mythology in Thursday (Thor's day) and French keeps Roman gods in mardi (Mars) and jeudi (Jupiter), Greek weekday names come almost entirely from the Orthodox church calendar. Five of the seven days are simply ordinal numbers, "second," "third," "fourth," and so on, counted from Sunday, and the remaining two trace back to religious observance rather than astronomy. Here is each one, in order, with pronunciation and where the name actually comes from.
Short answer: Sunday is Kyriaki ("the Lord's day"), and Monday through Thursday are simply the ordinal numbers second through fifth (Deftera, Triti, Tetarti, Pempti), counted from Sunday as day one. Friday, Paraskevi, means "preparation," and Saturday, Savvato, comes directly from the Hebrew word for Sabbath.
Modern Greek weekday names largely replaced the old Greco-Roman planetary system somewhere in the early Christian centuries, as the church calendar became the dominant organizing structure for the week across the Greek-speaking world. What survived is this numbered, church-anchored pattern, still used exactly as it was centuries ago.
Kyriaki comes from the Ancient Greek phrase kyriake hemera, "the Lord's day." Unlike English, where Sunday traces back to a pre-Christian term tied to the sun, Greek's word for Sunday is entirely a Christian coinage, and it also functions as the anchor day the other names count outward from, according to Wiktionary's etymology entry.
Deftera simply means "second." With Kyriaki counted as the first day of the week, Monday becomes the second, and the name is literally the feminine form of the ordinal number two, agreeing with the implied feminine noun hemera (day). No mythology, no planet, just a number.
Triti means "third," continuing the same ordinal pattern from Kyriaki. It comes from the Ancient Greek trite hemera, "third day," the same root that gives English words like "trilogy" and "triangle" their tri- prefix.
Tetarti means "fourth," from the same tetra- root found in words like "tetragon." It follows the identical ordinal logic as Deftera and Triti before it, simply counting one day further from Sunday.
Pempti means "fifth," from pente, the same root behind "pentagon" and "Pentecost." It is the last of the purely numbered days, closing out the run from Kyriaki through Thursday before the naming pattern shifts entirely for the final two days.
Here the pattern breaks. Paraskevi means "preparation," inherited from Ancient Greek paraskeue, and it marks the day of preparing for the Sabbath, a meaning rooted in Jewish and early Christian practice around observing Saturday as a day of rest. It is also a common Greek given name, since Agia Paraskevi (Saint Paraskevi) is a widely venerated Orthodox saint.
Savvato comes directly from Koine Greek sabbaton, itself a loanword from the Hebrew shabbat, Sabbath. It is one of the clearest, most direct Hebrew borrowings sitting inside everyday modern Greek, carried through unbroken since antiquity, as confirmed by Wiktionary's entry for Savvato.
Most European languages, including English, French, Spanish, Italian, and German, kept some version of a much older system where each weekday is named after a planet, which in turn was named after a god: the Moon, Mars, Mercury, Jupiter, Venus, Saturn, and the Sun. English Thursday and Norse-influenced Germanic languages swapped in their own gods, which is why Thursday nods to Thor rather than Jupiter.
Greek had its own version of this system in antiquity too, but the Eastern Orthodox church calendar eventually reorganized the week around Kyriaki, the Lord's day, as the anchor point, and numbered the following weekdays outward from it. Friday and Saturday kept their religious, non-numeric names because of their specific role in Sabbath observance, while Monday through Thursday were absorbed into the simpler ordinal counting system. The result is a set of weekday names that reads almost like a countdown, once you know what to listen for.
Greek is not alone in this. Portuguese also mostly avoids the planetary system, using segunda-feira, terca-feira, and so on for Monday through Friday, for very similar church-calendar reasons. Russian follows a related but distinct ordinal logic as well. It is a smaller group globally compared to the planet-based naming used across most of Western Europe, which makes it a genuinely interesting linguistic outlier rather than just a quirky footnote.
Because five of the seven weekday names are just ordinal numbers wearing a feminine ending, learning the days of the week doubles as a running start on Greek numbers. Deftera, Triti, Tetarti, and Pempti map directly onto deftero (second), trito (third), tetarto (fourth), and pempto (fifth) in their more general forms, used for ranking or ordering things outside of the calendar too.
That overlap is worth leaning into rather than memorizing the seven days as an unrelated list. Once "third" and Triti are linked in your head, recognizing tetarti as "fourth" and pempti as "fifth" becomes far more predictable, instead of seven separate words competing for space in memory.
Knowing the etymology is satisfying, but the days of the week are also some of the most frequently used vocabulary in any language, showing up in scheduling, travel plans, and everyday small talk almost immediately. A learner who can confidently say "I'll see you Triti" or ask "Is the shop open Kyriaki?" gets a lot of practical mileage out of just seven words.
Games built around real-world context tend to help this kind of vocabulary stick better than a printed list, since the words come attached to a situation, a calendar, a schedule, a conversation, rather than sitting in isolation. Noun Town takes that approach across its full vocabulary set, pairing native speaker audio with spaced repetition so words like these resurface for review right as you are about to forget them.
Want to build Greek vocabulary through real context instead of flashcards alone?
Try Noun Town on SteamSunday is Kyriaki, Monday is Deftera, Tuesday is Triti, Wednesday is Tetarti, Thursday is Pempti, Friday is Paraskevi, and Saturday is Savvato. Five of the seven are built from ordinal numbers, while Friday and Saturday have separate religious origins.
Deftera means "second" in Greek. In the Orthodox Christian calendar that shaped the modern Greek weekday names, Kyriaki (Sunday, the Lord's day) counts as the first day of the week, which makes Monday the second day, Tuesday the third, and so on.
No. Deftera, the Greek word for Monday, comes from the ordinal number "second" and has no connection to any letter of the Greek alphabet. The similarity some learners notice is coincidental, the naming pattern for Greek weekdays is based on counting days of the week, not the alphabet.
Kyriaki comes from the Ancient Greek phrase kyriake hemera, meaning "the Lord's day." Unlike English, where Sunday derives from a pre-Christian, sun-worship-linked term, Greek's word for Sunday reflects its Christian, ecclesiastical origin instead of an older planetary or solar naming system.
Paraskevi comes from Ancient Greek word for "preparation." It originally marked the day of preparing for the Sabbath, a meaning that carried into Christian tradition since Friday precedes Saturday, historically observed as the day of rest.
Savvato comes from the Koine Greek sabbaton, which itself derives from the Hebrew word for Sabbath. It is one of the clearest examples of a Hebrew loanword sitting inside the modern Greek calendar, carried across through Koine Greek.
No, and that is what makes Greek unusual among European languages. English, French, and other Germanic and Romance languages largely kept a planetary naming system tied to gods (Monday to the Moon, Thursday to Thor or Jupiter, and so on). Modern Greek replaced that older pattern with an ordinal, church-calendar based system, so its weekday names reflect Christian religious history rather than astronomy or mythology.
No, several languages influenced by Eastern Orthodox Christianity use a similar ordinal, church-based pattern, including Russian and Portuguese, which also largely avoid the planetary naming system. It is a smaller group compared to the planet-based naming used across most of Western Europe.
Roughly: Kyriaki (kir-ee-ah-KEE), Deftera (THEF-teh-rah), Triti (TREE-tee), Tetarti (teh-TAR-tee), Pempti (PEMB-tee), Paraskevi (pah-rah-skeh-VEE), and Savvato (SAH-vah-toh). Stress generally falls on the syllable shown in capitals, though natural speech varies slightly by region.
All seven are feminine nouns, since each one is really a shortened form of an adjective agreeing with the feminine Greek word for day, hemera. That is why Kyriaki, Deftera, and the rest all end in the feminine -i sound rather than a masculine or neuter ending.
Very useful. Days of the week come up constantly in scheduling, travel, and everyday conversation, and because five of the seven follow the same ordinal number pattern, they reinforce Greek numbers at the same time, making them one of the higher-value vocabulary sets for an early learner.