Meaning

verb to believe especially on uncertain or tentative grounds

verb 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

verb reflect deeply on a subject

originBorrowed from Latin speculātus, perfect active participle of speculor (“to watch, observe, examine, spy”) (see -ate (verb-forming suffix)), from specula (“a watchtower”), ultimately from speciō (“to look at”).

Etymology from Wiktionary, CC BY-SA 3.0