そのうわさは一体本当だろうか。

that (something or someone distant from the speaker, close to the listener; actions of the listener, or ideas expressed or understood by the listener); the; um...; er...; uh...

rumour; rumor; report; hearsay; gossip; common talk

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

...the heck (e.g. "what the heck?"); ...in the world (e.g. "why in the world?"); ...on earth (e.g. "who on earth?"); one object; one body; unity; one form; one style; one Buddhist image (or carving, etc.); generally; in general

truth; reality; actuality; fact; proper; right; correct; official; genuine; authentic; natural; veritable

be; is; indicates past or completed action; indicates light imperative

indicates a question (sometimes rhetorical); or; whether or not; some- (e.g. something, someone); indicates doubt, uncertainty, etc.; emphatic prefix; suffix forming adjectives or adverbs; in that way