na-adjective
experimental; trial; provisional
Describes something done on a trial basis, not yet permanent or final. Often used for preliminary measures, test implementations, or provisional arrangements.
このシステムはまだ試験的な段階です。
This system is still at an experimental stage.
試験的
We tried introducing the new rules on a trial basis.
仮 is a prefix meaning 'temporary' or 'provisional' (e.g., 仮設, 仮免許). 試験的 is an adjectival noun that describes the nature of an attempt or trial.
Compound of 試験 (test, trial) + 的 (-like, -al). The suffix 的 derives from Chinese 的 (de), used to form adjectival nouns.