speculative
Describes actions, investments, or attitudes based on speculation rather than certainty. Often used in financial contexts.
彼の投資は投機的だ。
His investments are speculative.
投機的な
Speculative behavior carries high risk.
Derived from 投機 (speculation) + 的 (adjectival suffix). The exact historical derivation of 投機 is uncertain, but it is conventionally associated with speculative investment.