unutterable

English Thesaurus

1. very difficult to pronounce correctly (adj.all)

similar	:	incommunicative, uncommunicative,
definition	:	not inclined to talk or give information or express opinions (adj.all)

2. defying expression or description (adj.all)

similar	:	inexpressible, unexpressible,
definition	:	defying expression (adj.all)

3. too sacred to be uttered (adj.all)

similar	:	sacred,
definition	:	concerned with religion or religious purposes (adj.all)