INTER'CALAR INTER'CALARY, adjective [Latin intercalarius; inter and calo, to call or proclaim.] Inserted; an epithet given to the odd day inserted in leap year. The twenty ninth of February in leap year is called the intercalary day. We read in Livy of an intercalary month.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI