The Collaborative International Dictionary of English v.0.48:
Hematemesis \Hem`a*tem"e*sis\, n. [NL., fr. Gr. a"i^ma, a"i`matos, blood + ? a vomiting, fr. ? to vomit.] (Med.) A vomiting of blood. [1913 Webster]WordNet (r) 3.0 (2006):
hematemesis n 1: vomiting blood [syn: hematemesis, haematemesis]