StringEndsQ¶ $ wo 'StringEndsQ["Hello World!", "World!"]' True $ wo 'StringEndsQ["Hello World!", "Moon!"]' False The one-argument operator form applies to a string later, e.g. inside Select. $ wo 'Select[{"CAC1", "CTG1", "ACT1", "CGA1", "CTC1"}, StringEndsQ["C1"]]' {CAC1, CTC1}