する(すいそくする)  Formal word for ‘speculate’. “It’s too early to speculate about the economy.” “Scientists speculate that...”  Unless you’re being quoted in a newspaper, don’t use 推測 yourself.
(すいり) Deductive reasoning, inference. Noun, not verb. A detective working from clues. Foreigners complain that in Japanese, you have to deduce the subject of the sentence, since Japanese usually omit it!
する(さっする) Infer the feelings of other people (usually in the sense of being a good host or sensitive friend) (as opposed to the related expression 気が利く, which refers to actually physically doing something for that person – like when you go to a host club and Dude lights your cigarette without you asking).
(すいさつ /) Close to 推理 and 推測、but less common. 推察 means, to guess or speculate about the meaning of someone’s behavior or words. 推察 is only used when you have no real proof.
(すいてい) Noun, not verb:a guess, an estimate.
(おす) Infer. Not often used. Also can mean to recommend someone for a job. To support a politician.
(おくそく) Wild guess. Unfounded guess. Guessing because you don’t have any other options. A shot in the dark.
Guess is a hard word to translate!  Because A) there are 6 or so words that your dictionary will define as ‘guess,’ and B) normally Japanese people don’t use ANY of those words, preferring to use 2 OTHER, seemingly unrelated verbs, in an idiomatic manner: 1) 何と思う? 2) 当ててみて!(literally, ‘try to hit!’) (guess my age!) However, here’s the rest of the ‘guess’ words: