(biology, anatomy) a tentacle: specifically, either of the two tentacles of a squid or cuttlefish that are longer than the other eight (technically called “arms”)

having confidence in one's skill; confident that one has the skill

(idiomatic, usually cooking) to display one's ability

arm wrestling

using someone's arm as a pillow

to use someone's arm as a pillow

a forearm; an antebrachium

black belt

(physics) conduction band; a range of electron energies in an insulator or semiconductor in which electrons can move freely and transport charge.

(physics) valence band; a highest range of electron energies in an insulator or semiconductor that can be populated; it corresponds to the valence electrons of the constituent atoms