seamless adj.

Middle English seme, from Old English  seam, "seam of a garment, suture, junction made by sewing together the edges of two pieces of cloth or two edges of the same piece," from Proto-Germanic *saumaz (source also of Old Frisian sam "hem, seam," Old Norse saumr, Middle Dutch som, Dutch zoom, Old High German soum, German Saum "hem"), from PIE root *syu- "to bind, sew."

Chidynge and reproche ... vnsowen the semes of freendshipe in mannes herte. [Chaucer, "Parson's Tale," c. 1386]

In Middle English also "a gash or scar" (c. 1400). Meaning "raised band of stitching on a ball" is recorded from 1888. Geological sense of "thin strata between two wider ones" is from 1590s. Figurative phrase bursting at the seams, expressive of overfullness, is by 1962. Seam-squirrel "a louse" was old U.S. slang (1893).

word-forming element meaning "lacking, cannot be, does not," from Old English -leas, from leas "free (from), devoid (of), false, feigned," from Proto-Germanic *lausaz (cognates: Dutch -loos, German -los "-less," Old Norse lauss "loose, free, vacant, dissolute," Middle Dutch los, German los "loose, free," Gothic laus "empty, vain"), from PIE root *leu- "to loosen, divide, cut apart." Related to loose and lease.