莫名 is a stative verb meaning 'indescribable' or 'inexpressible' — it describes a feeling or quality that cannot be put into words. It is most commonly used in the fixed phrase 莫名其妙 (mò míng qí miào, 'baffling / without rhyme or reason'), but can also appear alone before nouns like 恐惧 (fear) or 悲伤 (sadness) to mean 'a nameless / inexplicable kind of...'. As an s.v., it can be modified by degree adverbs like 很 or 十分.