邀请函用英语叫做 invitation。邀请函的来源是源自拉丁语，invitatio 意思是邀请。例句：

We are pleased to invite you to our wedding on Friday, July 10th at 6pm.

You are cordially invited to a dinner party to celebrate the birthday of John and Jane.

Please join us for a special screening of the new movie followed by a Q&A with the director.