In*ter"ca*late (?), v. t. [imp. & p. p. Intercalated (?); p. pr. & vb. n. Intercalating (?).] [L. intercalatus, p. p. of intercalare to intercalate to intercalate; inter between + calare to call, proclaim. See Calendar.]

1. (Chron.) To insert, as a day or other portion of time, in a calendar.

2. To insert among others, as a verse in a stanza; specif. (Geol.), to introduce as a bed or stratum, between the layers of a regular series of rocks.

Beds of fresh-water shells . . . are intercalated and interstratified with the shale.

• to insert an extra, leap, day into a calendar in order to maintain synchrony with natural phenomena.
  
• to insert an extra month into a calendar for the same purpose. The Hebrew calendar has such a month.