Taylor Swift Files Trademark for 'Big Reputation' |

Taylor Swift is banking on her reputation ... check that, her "Big Reputation," and ditto on her signature.

The singer's company -- TAS Rights Management, LLC -- filed docs to lock down the rights to "Big Reputation" ... which is a lyric in her song "End Game," off her latest album, "Reputation."

Taytay's looking to slap "Big Reputation" on a bunch of merch -- including sunglasses, cell phone cases, pajamas and gloves. She's also locking down her "Taylor Swift" signature ... for bathrobes, hair pins, dolls and toy glow sticks.

It's interesting ... she's been hawking merch with her signature since 2009, but the trademark move would give her more legal protection against knockoffs. Take that, piracy!