late 14c., "have a strong effect on the mind or heart, to stamp deeply in the mind," from Latin impressus, past participle of imprimere "press into or upon, stamp," also figurative, from assimilated form of in- "into, in, on, upon" (from PIE root *en "in") + premere "to press, hold fast, cover, crowd, compress" (from PIE root *per- (4) "to strike"). Literal sense of "to apply with pressure, make a permanent image in, indent, imprint" is from early 15c. in English. Related: Impressed; impressing.
Proto-Indo-European root meaning "to strike," an extended sense from root *per- (1) "forward, through."
It forms all or part of: compress; depress; espresso; express; impress (v.1) "have a strong effect on the mind or heart;" imprimatur; imprint; oppress; oppression; pregnant (adj.2) "convincing, weighty, pithy;" press (v.1) "push against;" pressure; print; repress; reprimand; suppress.