(1) A term meaning the same as closed when applied to syllables. See closed syllable. A checked vowel is one which appears in a closed syllable.
(2) The name of a binary feature proposed by Jakobson, Fant & Halle. [+checked] sounds have accompanying glottal closure or compression and include ejectives and implosives.
Jakobson R., Fant G. & Halle M. (1952) Preliminaries to speech analysis M.I.T.