invitation Look up invitation at Dictionary.com
mid-15c., from L. invitationem (nom. invitatio) "invitation," from invitatus, pp. of invitare "invite, treat, entertain," originally "be pleasant toward," from in- "toward," second element obscure, one suggestion is a lost word *vitus "pleasant." Meaning "the spoken or written form in which a person is invited" is from 1610s.