The Collaborative International Dictionary
Taenidium
Taenidium \T[ae]*nid"i*um\, n.; pl. T[ae]nidia. [NL., dim. fr. L. taenia a ribbon.] (Zo["o]l.) The chitinous fiber forming the spiral thread of the trache[ae] of insects. See Illust. of Trachea.
Wiktionary
taenidium
n. (context zoology English) The chitinous fibre forming the spiral thread of the tracheae of insects.