"disreputable, vulgar," 1794, from low (adj.) + life (n.). As a noun, also lowlife, "coarse, no-good person," from 1911. Low-lived (adj.) is attested from 1760.

1957, in reference to automobile wheels, from low (adj.) + profile (n.). General sense is by 1970 in American English, apparently first in reference to Nixon Administration policy of partial U.S. disengagement from burdensome commitments abroad.

"large beam going from wall to wall; girder which holds the sides of a building or ship together," c. 1400, from cross- + beam (n.).

1869; see beam (n.). So called for its shape. I-bar is from 1890; also I-rail (1873).

also low down, lowdown, "vulgar, far down the social scale," 1888, from low (adj.) + down (adv.). Earlier it had meant "humble" (1540s). As a noun, 1915, from the adjective, American English. Low-downer was late 19c. American English colloquial for "poor white; rude, mean person."

by 1895, perhaps 1847, from low key in some sense relating to deep musical tone or quiet sound; see low (adj.) + key (n.1). Low key in reference to a quiet voice is attested from 1837. Also compare undertone.

1868, from low (adj.) + class (n.). Earlier were low-born (c. 1200), low-bred (1757).

"lacking lofty or noble aspirations," c. 1740, see low (adj.)) + -minded.

1939, originally of motion pictures, "made with little expense;" from low (adj.) + budget (n.). Usually with a suggestion of low quality as a result.

of buildings, 1957, in contrast to high-rise; see low (adv.) + rise (v.).