| verb | to believe especially on uncertain or tentative grounds “Scientists supposed that large dinosaurs lived in swamps” |
| 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 “We were speculating whether the President had to resign after the scandal” |
| verb | reflect deeply on a subject “I mulled over the events of the afternoon” |
| verb | invest at a risk “I bought this house not because I want to live in it but to sell it later at a good price, so I am speculating” |
| speculative | adjective | not based on fact or investigation |
| speculation | noun | a hypothesis that has been formed by speculating or conjecturing (usually with little hard evidence) |
| speculator | noun | someone who makes conjectures without knowing the facts |
| theorizer | noun | someone who theorizes (especially in science or art) |
| theory | noun | a belief that can guide behavior |
| theoriser | noun | someone who theorizes (especially in science or art) |
| theorisation | noun | the production or use of theories |
| conjecture | noun | reasoning that involves the formation of conclusions from incomplete evidence |
| hypothesis | noun | a message expressing an opinion based on incomplete evidence |
| supposition | noun | the cognitive process of supposing |
| supposal | noun | the cognitive process of supposing |
| meditative | adjective | deeply or seriously thoughtful |
| meditation | noun | continuous and profound contemplation or musing on a subject or series of subjects of a deep or abstruse nature |
| ponderer | noun | a reflective thinker characterized by quiet contemplation |
| excogitative | adjective | concerned with excogitating or having the power of excogitation |
| contemplative | adjective | deeply or seriously thoughtful |
| contemplation | noun | a calm, lengthy, intent consideration |
| muse | noun | the source of an artist's inspiration |
| muser | noun | a reflective thinker characterized by quiet contemplation |
| musing | noun | a calm, lengthy, intent consideration |
| reflective | adjective | deeply or seriously thoughtful |
| muller | noun | a reflective thinker characterized by quiet contemplation |
| ruminative | adjective | deeply or seriously thoughtful |
| rumination | noun | a calm, lengthy, intent consideration |
| ruminator | noun | a reflective thinker characterized by quiet contemplation |