SOFFIT
soffit
(noun) the underside of a part of a building (such as an arch or overhang or beam etc.)
Source: WordNet® 3.1
Etymology
Noun
soffit (plural soffits)
(architecture) The visible underside of an arch, balcony, beam, cornice, staircase, vault or any other architectural element.
(pipe technology) The top point of the inside open section of a pipe or box conduit.
Source: Wiktionary
Sof"fit, n. Etym: [It. soffitta, soffitto, fr. soffiggere to hide,
properly, to fix or fasten under, L. suffigere to fasten beneath or
below; sub under, beneath + figere to fix, faste: cf. F. soffite.]
(Arch.)
Definition: The under side of the subordinate parts and members of
buildings, such as staircases, entablatures, archways, cornices, or
the like. See Illust. of Lintel.
Source: Webster’s Unabridged Dictionary 1913 Edition