Synonyms for Hypo (same or very similar meaning)
WordNet sense 1 (a compound used as a fixing agent in photographic developing):
sodium thiosulfate, sodium thiosulphateWordNet sense 2 (a piston syringe that is fitted with a hypodermic needle for giving injections):
hypodermic, hypodermic syringeFrom the ODE community, based on WordNetadd/edit