Synonyms for swear
verb
To curse
blaspheme, utter profanity, cuss*; see curse 1, 2.
To take an oath
avow, affirm, depose, testify, state, vow, attest, warrant, vouch, assert, swear by, make an affidavit, give witness, cross one's heart.
To declare
assert, affirm, maintain; see declare 1, justify 2.
See swear in Webster's New World Roget's A-Z Thesaurus II
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