contemplate vs speculate

contemplate and speculate both are verbs.

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

As verbs, contemplate and speculate are synonyms defined as:

Other synonyms of contemplate include chew over, excogitate, meditate, mull, mull over, muse, ponder, reflect, ruminate, think over.

contemplate (verb)	speculate (verb)
think intently and at length, as for spiritual purposes	reflect deeply on a subject
reflect deeply on a subject	to believe especially on uncertain or tentative grounds
consider as a possibility	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
look at thoughtfully; observe deep in thought	invest at a risk