Emily Dickinson Lexicon

cap, n. [OE cæppe < It. cappa, cloak, cape, or cope.]

1. Bonnet; crown; crest; cowl; head-covering; hood of a cloak; [fig.] head feathers.
2. Pileum; top of a bird's head.
3. Plug; ball; slug; bullet; detonating device; [fig.] thunder head; storm cloud; mass of unstable air.