prejudicial adj.

c. 1300, "despite, contempt," from Old French prejudice "a prejudice, prejudgment; damage" (13c.) and directly from Medieval Latin prejudicium "injustice," from Latin praeiudicium "prior judgment, judicial examination before trial; damage, harm," from prae- "before" (see pre-) + iudicium "judgment," from iudex (genitive iudicis) "a judge" (see judge (n.)).

Meaning "injury, physical harm" is mid-14c., as is the legal sense of "detriment or damage caused by the violation of a legal right." Meaning "preconceived opinion" (especially but not necessarily unfavorable) is from late 14c. in English; now usually "decision formed without due examination of the facts or arguments necessary to a just and impartial decision." To terminate with extreme prejudice "kill" is by 1972, said to be CIA jargon.

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).