In‐ter″ca‐la‐ry (?; 277), a. [L. intercalaris, intercalarius: cf. F. intercalaire. See Intercalate.]
1. (Chron.) Inserted or introduced among others in the calendar; as, an intercalary month, day, etc.; — now applied particularly to the odd day (Feb. 29) inserted in the calendar of leap year. See Bissextile, n.
2. Introduced or inserted among others; additional; supernumerary. “Intercalary spines.” Owen.
This intercalary line... is made the last of a triplet. Beattie.
Intercalary day(Med.), one on which no paroxysm of an intermittent disease occurs. Mayne.