-less, suffix forming adjectives and adverbs:
1 from nouns, meaning 'not having, without, free from' (doubtless; powerless).
2 from verbs, meaning 'not affected by or doing the action of the verb' (fathomless; tireless).
-lessly suffix forming adverbs. -lessness suffix forming nouns.
OE -leas f. leas devoid of