What does "thesis" mean?

1. (central argument) the main idea or theory that you want to prove in a piece of writing or a speech. 2. (music/poetry beat) the part of a rhythm that is not stressed, or the downward movement of a conductor's hand.

thesis

US //ˈθisəs// UK //θˈiːsɪs// the·sis

1 central argument (n.)
B2 Upper Intermediate Academic

the main idea or theory that you want to prove in a piece of writing or a speech.

a proposition or statement maintained by argument; the central premise of a rhetorical or logical work.

Example

The student's main thesis was that social media has changed how we make friends.

Example

The author's central thesis—that economic stability is a prerequisite for democratic growth—is supported by extensive historical data.
2 music/poetry beat (n.)
C2 Proficiency Technical Music

the part of a rhythm that is not stressed, or the downward movement of a conductor's hand.

the unstressed part of a poetic foot or a musical measure; also the downbeat in conducting.

Example

The conductor marked the thesis of the bar with a clear downward motion.

Example

In classical prosody, the distinction between arsis and thesis is essential for understanding the rhythmic structure of the verse.
- downbeat
- arsis

Origin

From Late Middle English thesis (“lowering of the voice”) and also borrowed directly from its etymon Latin thesis (“proposition, thesis; lowering of the voice”), from Ancient Greek θέσῐς (thésĭs, “arrangement, placement, setting; conclusion, position, thesis; lowering of the voice”), from τῐ́θημῐ (tĭ́thēmĭ, “to place, put, set; to put down in writing; to consider as, regard”) (ultimately from Proto-Indo-European *dʰeh₁- (“to do; to place, put”)) + -σῐς (-sĭs, suffix forming abstract nouns or nouns of action, process, or result). The English word is a doublet of deed. Sense 1.1 (“proposition or statement supported by arguments”) is adopted from antithesis. Sense 1.4 (“initial stage of reasoning”) was first used by the German philosopher Johann Gottlieb Fichte (1762–1814), and later applied to the dialectical method of his countryman, the philosopher Georg Wilhelm Friedrich Hegel (1770–1831). The plural form theses is borrowed from Latin thesēs, from Ancient Greek θέσεις (théseis).