"type of long, slender, voracious freshwater fish," early 14c., pik (mid-12c. in place names), probably short for pike-fish, a special use of pike (n.2) in reference to the fish's long, pointed jaw, and in part from French brochet "pike" (fish), from broche "a roasting spit." In Middle English, proverbial for health and vigor.
"state or condition of being weak or feeble, lack of strength or vigor," early 15c., from Old French debilite (Modern French débilité) or directly from Latin debilitatem (nominative debilitas) "a laming, crippling, weakening," from debilis "lame, disabled, crippled," figuratively "weak, helpless," from de "from, away" (see de-) + -bilis "strength," from PIE root *bel- "strong" (see Bolshevik).
"liveliness, vivacity," 1734, from Italian brio "mettle, fire, life," perhaps a shortened derivative of Latin ebrius "drunk." Or via Provençal briu "vigor," from Celtic *brig-o- "strength," from PIE root *gwere- (1) "heavy." Probably it entered English via the musical instruction con brio.
early 15c., "without vital force, having lost life," from Late Latin inanimatus "lifeless," from in- "not" (see in- (1)) + animatus (see animation). The Latin word closest corresponding in form and sense is inanimalis. Meaning "lacking vivacity, without spirit, dull" is from 1734. Inanimate as a verb meant "infuse with life or vigor" (17c.), from the other in- (see in- (2)).
late 12c., "lacking strength or vigor" (physical, moral, or intellectual), from Old French feble "weak, feeble" (12c., Modern French faible), a dissimilation of Latin flebilis "lamentable," literally "that is to be wept over," from flere "weep, cry, shed tears, lament" (from PIE *bhle- "to howl;" see bleat (v.)). The first -l- was lost in Old French. The noun meaning "feeble person" is recorded from mid-14c.