the last (24th) letter of the Greek alphabet
"The professor wrote the symbol omega on the blackboard to represent the final element in their mathematical sequence."
The twenty-fourth letter of the Classical and the Modern Greek alphabet, and the twenty-eighth letter of the Old and the Ancient Greek alphabet, i.e. the last letter of every Greek alphabet. Uppercase version: Ω; lowercase: ω.
"The professor corrected our essay because we accidentally wrote "omega" instead of the number zero in the equation."
In plain English: Omega is the last letter of the Greek alphabet, often used to represent the end or final stage of something.
"The omega was the last letter in the Greek alphabet that students had to memorize for their test."
Usage: Use "omega" to refer to the final letter of the Greek alphabet or as a symbol representing an ultimate end in phrases like "the beginning and the omega." Avoid using it for general endings, as that is not its standard everyday meaning.
The word comes from the Ancient Greek phrase "ô méga," which literally means "great omega." It was adopted into Middle English with this same reference to the letter's role as a long vowel.