Origin and history of linearity

1640s, "resembling a line, of or pertaining to lines," from French linéaire, from Latin linearis "belonging to a line," from linea "string, line" (see line (n.)). Essentially the same word as lineal; "in Latin linearis the original suffix -alis was changed to -aris by dissimilation, but in Late Latin this rule was no longer productive and the formation or re-formation in -alis remained unchanged." [Barnhart].

As "involving the use of lines" from 1840, hence Linear A, Linear B, names given (1902-3) to two related forms of linear Minoan writing discovered 1894-1901 in Crete by Sir Arthur Evans and long defying translation. It is used thus in opposition to pictographic.

word-forming element making abstract nouns from adjectives and meaning "condition or quality of being ______," from Middle English -ite, from Old French -ete (Modern French -ité) and directly from Latin -itatem (nominative -itas), suffix denoting state or condition, composed of -i- (from the stem or else a connective) + the common abstract suffix -tas (see -ty (2)).

Roughly, the word in -ity usually means the quality of being what the adjective describes, or concretely an instance of the quality, or collectively all the instances; & the word in -ism means the disposition, or collectively all those who feel it. [Fowler]