1. (Geology) interleaved, formed in distinctly alternating layers. (wiktionary.org)
2. Interpolate (an intercalary period) in a calendar. (Google Dictionary)
3. Insert (something) between layers in a crystal lattice, geological formation, or other structure. (Google Dictionary)
4. Interposed; inserted between two others. (biology-online.org)
Word origin: From Latin intercalatus, past participle of intercalare “to proclaim the insertion of an intercalary day,” from inter- “between” + calare “calendar”.