I think that when several consonants are joined together into a single bIja, as in Tantrism, they are sometimes called kUTAkSara-s, which I guess means "heap syllables," and that this applies to them both as pronounced and as written.  Is this terminology especially likely to be used when the consonants are many  in number (say, more than three) and are hard or virtually impossible to pronounce?

I don't have my dicionaries or books on Tantrism and indrajAla easily accessible at the moment so can't double-check before posting, or give examples.

Allen