— tachyphylactic /tak'euh fi lak"tik/ , adj.
/tak'euh fi lak"sis/ , n.
1. Med. immediate, temporary immunization against the effects of injection of a toxic extract owing to previous small injections of the same extract.
2. a decreased response to a medicine given over a period of time so that larger doses are required to produce the same response. Also, tachyphylaxia /tak'euh fi lak"see euh/ .
[ TACHY- + Gk phýlaxis a guarding, equiv. to phylak- (s. of phylássein to guard) + -sis -SIS ]