An archaic third-person singular present tense form of 'believe,' meaning 'believes' or 'has faith in.'
From Old English 'belyfan,' possibly from 'be-' (around) and 'leaf' (to remain/believe). The '-eth' ending is Early Modern English verb conjugation (1500s-1600s), used especially in the King James Bible.
The '-eth' ending is how we know when something is from the King James Bible or Shakespeare—'believeth' instead of 'believes,' 'hath' instead of 'has.' This form died out in spoken English by 1700, but it's frozen forever in these famous texts.
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