swim suit trunks??

[celraysoda2000]

Why are men’s swimsuits also called “trunks”?
-M

[Spectre_of_Pithecanthropus]

www.etymonline.com doesn’t have an entry for trunks, but it does for trunk, as in a tree trunk or the torso of a human body. This word is derived from the same root as truncate, i.e. to cut off. So I suspect that swimming trunks were originally “truncated” pants.

[RealityChuck]

The OED documents the progression:

IV. 17. pl. a. = TRUNK-HOSE. Obs.

1583 Rates of Custome Ho. Fj, Truncks the dosen xii. s. …
b. Short breeches of silk or other thin material; in theatrical use, often worn over tights; in quot. 1896 applied to ordinary breeches or knickerbockers.

1825 HONE Every-day Bk. I. 1463 Theatrical ‘trunks’, or short breeches. …

c. orig. U.S. Short tight-fitting drawers worn by swimmers and athletes. swimming trunks: see SWIMMING vbl. n. 6. 

1883 Pall Mall G. 26 July 7/1 Captain Webb attempted his perilous feat of swimming the Niagara Rapids… He wore a pair of silk trunks…

Going back to “Trunk-Hose,” the OED says:

[f. TRUNK (n. or v.1) + HOSE.
The sense of ‘trunk’ here, as in the later trunk-breeches, and the earlier TRUNK n. 17, appears to be uncertain. Various suggestions have been made, e.g. that trunk refers to the trunk of the body, or that it is TRUNK n. 13, ‘a hollow tube or pipe’; or that it is = truncate or truncated, as being, as it were, cut short. Early explanations have not been found: the term may have been of vulgar origin.]

So ultimately, there’s no sure answer.