speculate vs theorise

speculate and theorise both are verbs.

Word	Noun	Adjective	Verb	Adverb
speculate	No	No	Yes	No
theorise	No	No	Yes	No

As verbs, speculate and theorise are synonyms defined as:

speculate and theorise: to believe especially on uncertain or tentative grounds

Other synonyms of speculate include conjecture, hypothecate, hypothesise, hypothesize, suppose, theorize.

speculate (verb)	theorise (verb)
reflect deeply on a subject	to believe especially on uncertain or tentative grounds
to believe especially on uncertain or tentative grounds
talk over conjecturally, or review in an idle or casual way and with an element of doubt or without sufficient reason to reach a conclusion
invest at a risk