"of or pertaining to the pelvis," 1822, irregularly formed from pelvis + -ic. OED prefers "the better-formed" French pelvien.
Entries linking to pelvic
pelvis n.
"basin-like cavity formed by the bones of the pelvic girdle," 1610s, from Modern Latin, from Latin pelvis "basin, laver," Old Latin peluis "basin," from PIE *pel- "container" (source also of Sanskrit palavi "vessel," Greek pelex "helmet," pelike "goblet, bowl," Old Norse and Old English full "cup").
-ic
Middle English -ik, -ick, word-forming element making adjectives, "having to do with, having the nature of, being, made of, caused by, similar to," from French -ique and directly from Latin -icus or from cognate Greek -ikos "in the manner of; pertaining to." From PIE adjective suffix *-(i)ko, which also yielded Slavic -isku, adjectival suffix indicating origin, the source of the -sky (Russian -skii) in many surnames. In chemistry, indicating a higher valence than names in -ous (first in benzoic, 1791).
In Middle English and after often spelled -ick, -ike, -ique. Variant forms in -ick (critick, ethick) were common in early Modern English and survived in English dictionaries into early 19c. This spelling was supported by Johnson but opposed by Webster, who prevailed.