Avacana (nt.) [a + vacana] "non -- word", i. e. the wrong word or expression J i.410.

Pali-English Dictionary, TW Rhys Davids, William Stede,

a-vacana n. absence of a special assertion KātyŚr. &c
• (mfn.) not expressing anything Jaim
• not speaking, silent Śak

Sanskrit-English Dictionary, by M. Monier William

brjod du ma mchis pa

[tenses]

• brjod
• rjod
• brjod
• rjod

[translation-san] {L} anabhilāpya

[translation-san] {C} avacana

[translation-eng] {Hopkins} inexpressible; ineffable

[translation-eng] {C} cannot be spoken; cannot be expressed; beyond words

Jeffrey Hopkins' Tibetan-Sanskrit-English Dictionary