Ignescent

Part of speech: adjective

Pronunciation: /ɪɡˈnɛsənt/

Definitions

1. Capable of igniting or bursting into flame when exposed to air or upon friction
2. Tending to catch fire readily when exposed to air or subjected to friction
3. Readily inflammable or prone to spontaneous combustion when in contact with atmospheric oxygen

Etymology: "Ignescent" comes from the Latin "ignescens," the present participle of "ignescere," meaning "to become inflamed." That verb is built on "ignis," the Latin word for fire, and it is the same root that gives English words like "igneous" and "ignite." The ending "-escent" is a Latin suffix signalling a process of becoming, so the word's construction is transparent: something that is in the act of catching fire. French has a matching form, "ignescent," which suggests the word reached English through the same scholarly channel many technical Latinate terms did, rather than through everyday speech. Its use has stayed narrow, confined mostly to chemistry and older scientific writing about substances that ignite on their own.