toilsome (adj.)

[hard work] c. 1300, toile, "turmoil, violent contention, battle," senses now obsolete, from Anglo-French toil (13c.), from toiler "agitate, stir up, entangle, writhe about," from Old French toeillier "drag about, make dirty" (12c.), usually said (Watkins, etc.) to be from Latin tudiculare "crush with a small hammer," from tudicula "mill for crushing olives, instrument for crushing," from Latin tudes "hammer" (from PIE *tud-, variant of *(s)teu- "to push, stroke, knock, beat;" see obtuse).

The sense of "hard work, exhausting effort, labor accomplished with fatigue and pain" (1590s) is from the related verb (see toil (v.)) or from or reinforced by the notion of a "fight" with difficulties and obstacles.

word-forming element used in making adjectives from nouns or adjectives (and sometimes verbs) and meaning "tending to; causing; to a considerable degree," from Old English -sum, identical with some, from PIE root *sem- (1) "one; as one, together with." Cognate with Old Frisian -sum, German -sam, Old Norse -samr; also related to same.

"It usually indicates the possession of a considerable degree of the quality named: as mettlesome, full of mettle or spirit; gladsome, very glad or joyous" [Century Dictionary]. It is also, disguised, the ending in buxom. For the -some used with numbers (twosome, foursome, etc.), see -some (2).