Why was "tantrum" trending last week?
c.1200, from Old English holh (n.) "hollow place, hole," from Proto-Germanic *hul-, from PIE *kel- "to cover, conceal" (see cell). The figurative sense of "insincere" is attested from 1520s. Related: Hollowly; hollowness. To carry it hollow "take it completely" is first recorded 1660s, of unknown origin or connection.
late 14c., holowen, from hollow (adj.). Related: Hollowed; hollowing.
"lowland, valley, basin," 1550s, probably a modern formation from hollow (adj.). Old English had holh (n.) "cave, den; internal cavity."