Linear
mid 17th century: from Latin linearis, from linea ‘a line’ (see line1).
wiktionary
From Latin līneāris, from līnea(“line”) + -āris (adjectival suffix). Doublet of lineal.
etymonline
linear (adj.)
"resembling a line, of or pertaining to lines," 1640s, 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 there in opposition to pictographic.