Aksara (also akshara, Devanagari अक्षर, IAST akṣara) is a Sanskrit term translating to “imperishable, indestructible, fixed, immutable” (i.e. from a- “not” and kṣar- “melt away, perish”).
It has two main fields of application, in Sanskrit grammatical tradition (śikṣā) and in Vedanta philosophy. The uniting aspect of these uses is the mystical view of language, or shabda, in Hindu tradition, and especially the notion of the syllable as a kind of immutable (or “atomic”) substance of both language and truth, most prominently, the mystical syllable Aum, which is given the name of ekākṣara (i.e. eka-akṣara), which can be translated as both “the sole imperishable thing” and as “a single syllable”. In the explicitly monotheistic tradition of Bhakti yoga, both akṣara and aum become seen as a symbol or name of God.