late 14c. (possibly early 13c.), "rendered fat of a swine," from Old French larde "joint, meat," especially "bacon fat" (12c.), and directly from Latin lardum "lard, bacon, cured swine's flesh" (source also of Spanish, Italian lardo), probably cognate with Greek larinos "fat," laros "pleasing to the taste."
word-forming element denoting "belonging to, of the nature of," from Latin -aceus, enlarged form of adjectival suffix -ax (genitive -acis); see -acea. Especially in biology, "pertaining to X order of plants or animals."