Definition of halant:
(n) :
A diacritic used in most writing systems of the Indian subcontinent to signify the lack of an inherent vowel.
(n) :
A sign which serves the same purpose in any writing system.
(n) :
(computing) A character which binds consonants into a conjunct or some other form of visual combination which is prototypically a visual indication that the first consonant does not have an implicit vowel