Perhaps; probably; it is likely that—an archaic word meaning 'by likelihood.'
From be- + like (Old English gelic, meaning 'similar' or 'probable'). Middle English 'belike' literally meant 'by likelihood' and evolved into an adverb expressing probability.
Shakespeare used 'belike' constantly—it's the Elizabethan way of saying 'maybe!' The word shows how 'like' meant 'likely' back then, not just 'similar to,' and how one little morpheme can mean the difference between modern and archaic English!
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