1620s, "not direct or immediate," from consequent (Latin consequentia) + -al (1). Sense of "following as an effect or result" is from 1650s. Of persons, "self-important," 1758, from obsolete sense in reference to things, "important, pregnant with consequences" (1728). Related: Consequentially (c. 1600).
word-forming element making nouns implying a practice, system, doctrine, etc., from French -isme or directly from Latin -isma, -ismus (source also of Italian, Spanish -ismo, Dutch, German -ismus), from Greek -ismos, noun ending signifying the practice or teaching of a thing, from the stem of verbs in -izein, a verb-forming element denoting the doing of the noun or adjective to which it is attached. For distinction of use, see -ity. The related Greek suffix -isma(t)- affects some forms.
<a href="https://www.etymonline.com/word/consequentialism">Etymology of consequentialism by etymonline</a>
Harper, D. (n.d.). Etymology of consequentialism. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/consequentialism