(astronomy) A binary star whose component stars are in physical contact (share an upper atmosphere).

(ornithology) A call made between birds in a flock or a pair in order to maintain contact with one another when foraging, flying, etc.

plural of contact call

plural of language contact

(linguistics) The study of language contact

(linguistics) The phenomenon in which speakers of two or more languages or varieties interact and influence each other.

plural of contact binary

plural of non-contact

(mathematics, contact geometry) A smooth manifold of odd dimensionality in contact geometry.

plural of contact manifold