Webster’s Revised Unabridged Dictionary · 1913 Batement Bate′ment (·ment), n. [For Abatement. See 2d Bate.] Abatement; diminution. Moxon. Batement light (Arch.), a window or one division of a window having vertical sides, but with the sill not horizontal, as where it follows the rake of a staircase. ‹ Bateless Batfish ›