rectrices

noun, plural rec·tri·ces [rek-trahy-seez, rek-truh-seez] /rɛkˈtraɪ siz, ˈrɛk trəˌsiz/. Ornithology.

1. one of the tail feathers of a bird controlling direction during flight.

noun plural rectrices (ˈrɛktrɪˌsiːz, rɛkˈtraɪsiːz)

1. any of the large stiff feathers of a bird’s tail, used in controlling the direction of flight