experimental (adj.)

mid-14c., "action of observing or testing; an observation, test, or trial;" also "piece of evidence or empirical proof; feat of magic or sorcery," from Old French esperment "practical knowledge, cunning; enchantment, magic spell; trial, proof, example; lesson, sign, indication," from Latin experimentum "a trial, test, proof, experiment," noun of action from experiri "to try, test," from ex "out of" (see ex-) + peritus "experienced, tested," from PIE *per-yo-, suffixed form of root *per- (3) "to try, risk."

suffix forming adjectives from nouns or other adjectives, "of, like, related to, pertaining to," Middle English -al, -el, from French or directly from Latin -alis (see -al (2)).