Prone means naturally tending towards something, usually something bad. Accident-prone, prone to colds, prone to exaggerate.
It is always followed by to and almost always by an unwelcome outcome — prone to flooding, prone to error, prone to jealousy. Accident-prone is the fixed compound. The other sense is lying face down, against supine, which is face up: the prone position, and in shooting and first aid the distinction is technical and matters. Note proneness, which exists but is barely used.
1adjectiveproneNaturally tending towards something bad.
“He's prone to headaches when he doesn't get enough sleep.”
synonyms: liable, susceptible
2adjectivelyingLying face down.
“The injured player lay prone on the grass while the doctor checked his back.”
prone is a quality of tending or lying.
PRONE → a THRONE, and it rhymes
The king lies face down on the stone floor in front of his own empty throne, and nobody in the hall dares tell him to get up.
hooks ontothrone
Latin pronus meant bent forward, from pro, forward. The face-down sense is the literal one and the tending-towards sense is a lean of character rather than a lean of body.
Latin
prōnus — turned forward, bent or inclined
Middle English
prone
English, today
prone
Built from
From Middle English prone, proone, proon, from Latin prōnus (“turned forward, bent or inclined”), from prō (“forward”).
Etymology from Wiktionary, CC BY-SA
Practised in Sharper Adjectives