the adverb "tirelessly" is built upon the old english verb "tire," which originally meant to fail or become weary. the addition of the suffix "-less," meaning "without," transforms it into the adjective "tireless," describing one who is without weariness. finally, the adverbial suffix "-ly" modifies this quality into a manner of action. thus, the literal construction "in a manner without weariness" perfectly captures the modern sense of persistent, unflagging effort. its journey is purely germanic, with each morpheme maintaining a transparent link from its ancient sense to its current grammatical function.

Structure: tire (exhaust) + less (without) + ly (adverb suffix) tire: from old english teorian (to fail, cease, become weary), of unknown origin. functions as the core verb root meaning to exhaust or weary. less: from old english -lēas (devoid of, free from), from proto-germanic -lausaz. functions as an adjective-forming suffix meaning "without." ly: from old english -līce (like, having the form of), from proto-germanic -līkō. functions as an adverb-forming suffix.