She feigned interest in the joke, though she didn't find it funny at all.

feigned 是动词 feign 的过去式形式。feign 的意思是"假装、佯装"，通常指为了某种目的而故意表现出虚假的样子。这个词来自古法语，原意是"塑造、制造"，引申为"制造假象"的意思。