adj. 25B6; adjective
any discussion is largely speculative : CONJECTURAL, suppositional, theoretical, hypothetical, putative, academic, notional, abstract; tentative, unproven, unfounded, groundless, unsubstantiated.
a speculative investment : RISKY, hazardous, unsafe, uncertain, unpredictable; informal chancy, dicey, iffy; Brit. informal dodgy.