speculate vs contemplate

speculate and contemplate both are verbs.

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

As verbs, speculate and contemplate are synonyms defined as:

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

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