You are correct!
From our dictionary:
Yesterday's Word Quiz
Tomorrow's Word Quiz
(lu•kyOO'nu), —n., —pl. -nae (-nE), -nas.
1. a gap or missing part, as in a manuscript, series, or logical argument; hiatus.
2. Anat. one of the numerous minute cavities in the substance of bone, supposed to contain nucleate cells.
3. Bot. an air space in the cellular tissue of plants.
Fact Monster Word Quiz for Kids