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general::
Phrase(s): (I) can’t rightly say.
Rur. I do not know with any certainty. • Fred: When do you think we’ll get there? Bill: Can’t rightly say. • Bob: Okay, how does this look to you? Bill: I can’t rightly say. I’ve never seen anything like it before.
McGrawhill's American Idioms And Phrasal Verbs