From pleonasm +‎ -astic.

pleonastic (comparative more pleonastic, superlative most pleonastic)

1988 , Andrew Radford, chapter 6, in Transformational grammar: a first course , Cambridge, UK: Cambridge University Press, page 319:

characterised by redundancy or use of an excessive number of words

of, or relating to pleonasm

characterised by redundancy or the use of an excess number of words