The term 'like hen's teeth' is an idiom used to describe something that is very RARE or hard to find. This phrase can be broken down into three crossword solutions: RARE (4 letters), SCARCE (6 letters), and RET (3 letters). RARE means not common or occurring infrequently, SCARCE means not plentiful or available in small quantities, and RET means extremely RARE. All three words are used to describe something that is difficult to find or obtain.