This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Pertaining to reversion.

Pertaining to, or of the nature of, reversion; reversionary: specifically, relating to the appearance in any organism, plant or animal, of some character shown by its progenitors or presumably possessed by the ancestral form from which it is descended.

"On the other hand, to judge by the reversional traits which show themselves in individuals that vary from the prevailing predatory style of temperament, the ante-predatory variant seems to have a greater stability and greater symmetry in the distribution or relative force of its temperamental elements."