a <#stamp> paying the postage for <#airmail=air mail>.  Since 1977 Air Mail stamps are issued only for international air mail.  <#scott=Scott> numbers for air mail stamps are prefixed with C.

a <#stampenv=stamped envelope> intended for <#airmail=air mail> service.  <#scott=Scott> numbers for air mail stamped envelopes and <#aerogram=aerograms> are prefixed with UC.

see <#buffballoon=Buffalo Balloon> and <#rodgers=Rodgers Aerial Post>.

see <#amstamp=Air Mail Stamp>.

a <#stampenv=stamped envelope> on which the embossed stamp-like <#indicia=indicium> is entirely lacking in intended color.