défaillit

Défaillir is a French verb that covers several closely related meanings centered on loss of strength or coherence. In its most common sense, to défaillir means to faint or to lose consciousness, often as a reaction to heat, pain, or sudden physical stress. In this sense, the third-person singular present form is défaillit, as in il défaillit (he faints). The verb can also denote a broader failure or breakdown, as in a plan, a system, or an argument that collapses or becomes ineffective. In such uses, défaillir can appear in tenses such as the passé composé (il a défailli) or the present (le système défaillit).

Défaillir also exists as an adjective in its related form défaillant, describing something that is defective, unreliable, or prone to failure. A défaillant component, for example, is one that is not functioning properly, and a défaillance refers to the event or state of failing, malfunction, or breakdown. In medical terminology, défaillance is used in contexts such as défaillance d’organe (organ failure) or défaillance cardiaque (cardiac failure). In finance or law, défaillance can denote default or failure to meet obligations, as in the défaillance d’un emprunteur.

Usage and nuance: défaillir can convey sudden physical loss of strength, while défaillir can also describe systematic or ongoing weakness. The noun défaillance emphasizes a fault state or breakdown, whereas défaillant as an adjective highlights unreliability or defect. This term appears across medical, technical, and organizational contexts, always implying a disruption of normal function or capacity.