From Longman Dictionary of Contemporary Englishmethinksme‧thinks /mɪˈθɪŋks/ verb (past tense methought /-ˈθɔːt $ -ˈθɒːt/) [transitive] old use THINK ABOUTI think Methinks he is not mistaken.
Examples from the Corpus
methinks• They do with every other side - somehow methinks scum will avoid that on the whole.Origin methinks Old English me thincth “it seems to me”, from thyncan “to seem” 