English
cohomology
From co- + homology.
Proto-Indo-European *ḱóm ‘beside, near, by, with’
Proto-Italic *kom ‘with, along, at’
Proto-Italic *kom- ‘together’
English co-
Proto-Indo-European *sem- ‘together, one’
…
Ancient Greek ὁμός ‘same, common, joint’
Ancient Greek ὁμόλογος ‘in agreement, of one mind’
Ancient Greek ὁμολογία ‘agreement, assent’
Latin homologia
English homology
Today it means
noun A method of contravariantly associating a family of invariant quotient groups to each algebraic or geometric object of a category, including categories of geometric and algebraic objects.
Language periods are conventional ranges, not dates for this word.
Etymograph / cohomology