-less Also -lessness.
Without; unaffected by; failure or inability.
[Old English -lēas, from lēas, devoid of.]
Words in -less are nearly all adjectives. The great majority come from nouns and have the sense of lacking or being without that thing or quality: bottomless, childless, defenceless, lawless, pointless, spineless, strapless, toothless. The comparatively few that originate in verbs indicate something that is unaffected by the action or the verb, or some failure or inability to carry out that action: dauntless, quenchless, relentless, resistless, tireless.
The suffix is freely used to create new adjectives at need, to the extent that only a proportion of them can be recorded in dictionaries. Many are invented to fill a momentary need: girlfriendless, handbrakeless, monarchless, passwordless, sidewalkless.
Corresponding nouns are formed by adding -ness: childlessness, fearlessness, tastelessness.