1670s, "having the form of a tube or pipe," from Latin tubulus "a small pipe" (see tube) + -ar. Teen slang sense attested by 1982, Valspeak, apparently from surfers' use of tube as slang for a hollow, curling wave, ideal for riding (1962).
1610s, from French tube (15c.), from Latin tubus "tube, pipe," a word of unknown origin. The London subway was christened the Twopenny Tube by 1900 (H.D. Browne, in the "Londoner" of June 30); tube for "cylindrical railway tunnel" is attested from 1847. The meaning "TV as a medium" is from 1959, short for cathode ray tube or picture tube. Tube top as a women's clothing style is attested from 1972. Tube steak is attested from 1963 as "frankfurter," slang meaning "penis" is recorded by mid-1980s.
word-formation element meaning "pertaining to, of the nature of," from Latin -arem, -aris "of the kind of, belonging to," a secondary form (by dissimilation) of -alis, used after syllables with an -l- (such as insularis for *insulalis, stellaris for *stellalis).
<a href="https://www.etymonline.com/word/tubular">Etymology of tubular by etymonline</a>
Harper, D. (n.d.). Etymology of tubular. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/tubular