Unreliability

Part of speech: noun

Definitions

1. The condition of exhibiting unpredictable behavior or performance
2. The quality of being unreliable or failing to perform consistently in expected ways
3. A state characterized by the inability to be trusted or counted on routinely

Etymology: "Unreliability" is simply "un-" attached to "reliability," so the interesting history lies in the pieces. The prefix "un-" is an ancient Germanic element, inherited through Old English and still productive in English. "Reliability" is built from "rely," which came into English from Old French "relier," meaning to bind or tie together, with the sense of trust developing later, plus the suffix "-able," traceable to Latin "-abilis." Its sense of trustworthiness is a fairly recent extension of the older idea of depending on something. The noun "unreliability" thus combines a native Germanic negative with a French-Latin stem, a pairing common in modern English. Its meaning, the quality of behaving unpredictably, follows directly from the negation of "reliable," so the word needed no separate invention of its own.

Synonyms: instability, unpredictability, inconsistency

Antonyms: reliability, dependability