I didn't think his comments were very appropriate at the time.

appropriate 是形容词，意思是"合适的、恰当的"。这个词由前缀 ad-（表示"朝向"）和词根 propri（来自拉丁语 proprius，意为"自己的、特有的"）组成，字面意思是"归属于自己的"，引申为"恰当的、得体的"。