Bif'i-lar, a.

a. [Lat. bis, twice, and filum, thread.] Two-threaded; involving the use of two threads; as, bifilar suspension, a bifilar balance.

Bifilar micrometer (often called a bifilar), an instrument for measuring minute distances or angles by means of two very minute threads (usually spider-lines), one of which, at least, is movable;—more commonly called a filar micrometer.