The OED lists three definitions:
1.
a. Characterized by or relating to avoidance (of something).
b. With preceding word: characterized by avoidance of the thing specified.
2. Biology and Psychology. Designating behaviour which tends to remove a person or animal from situations or stimuli which are perceived as harmful or unpleasant, esp. social ones; relating to or exhibiting such behaviour.
The examples for 1. a. range from 1794 to 1994. The oldest:
E. Williams Poems II. 232 There are three avoidant injunctions on the Bard: to avoid sloth..; to avoid contention..; and to avoid folly.
and the newest:
J. M. Gottman What predicts Divorce? i. 27 The typical defensive statement is self-protective and avoidant of blame and responsibility.