It's an old synonym for "recipe" as well as a paper acknowledging that something's in hand
... A receipt /r'sit/ is a piece of paper that confirms that money or goods 
have ... acknowledgment - a statement acknowledging something or someone; "
she... [DOC] [TLE] A New Step In Evolution  Phenomena [PAR] Jun 2, 2008 ... Lenski told me about the discovery behind the paper when I first met him a few 
years ago.