a.

1. 有……傾向的，易於……的[F][（+to）][+to-v]
   Mother is prone to headaches.

   我母親經常頭痛。

2. 俯伏的，面向下的
   He was lying prone on the couch, fast asleep.

   他俯臥在長榻上，睡得正香。

3. 傾斜的；陡的

adj.

1. [often in combination] likely or liable to suffer from, do, or experience (something unfortunate):
   accident-prone
   farmed fish are prone to disease.
2. lying flat, especially face downwards.
   ▸with the palm of the hand facing downwards.
3. archaic with a downward slope or direction.