She found it difficult to articulate her thoughts clearly.

articulate 是动词，由词根 articul-（来自拉丁语 articulus，意为"关节、连接"）和后缀 -ate（表示"使成为..."）组成。字面意思是"像关节一样连接起来"，引申为"清晰地表达"，指把想法像连接关节一样有条理地组织并表达出来。