FLEA

[flea] n [ME fle, fr. OE flea; akin to OHG floh flea] (bef. 12c): any of an order (Siphonaptera) of small wingless bloodsucking insects that have a hard laterally compressed body and legs adapted to leaping and that feed on warm-blooded animals -- flea in one's[ ]ear : rebuke "sent him away with a flea in his ear"