Citigroup is suing AT&T for using one of the most common words in the English language

Armed with a trademark on the term “thankyou,” Citigroup $C is suing AT&T $T for thanking its customers.

On June 2, AT&T launched a customer loyalty program called “AT&T thanks,” trademarking the name in connection with loyalty incentives. The program offers perks to customers, including those with the AT&T Universal Card, which has been co-branded with Citigroup since 1998.

Citigroup, meanwhile, has been using the term “thankyou” since 2004 to promote its own customer loyalty and rewards programs, including those associated with the AT&T Universal Card. It says AT&T’s new effort is “confusingly similar” and infringes on its trademark rights, according to a complaint filed in the US District Court in Manhattan on Friday (June 10).

The New York-based bank has trademarks on the phrases “thankyou” and “Citi thankyou,” as well as other variations of those terms, in connection with promoting banking or credit-card loyalty programs. Citigroup alleges that AT&T’s comparable use of the term “thanks” will likely confuse customers. Citi is seeking unspecified damages and asking a federal judge to block AT&T from using “thanks” and “AT&T thanks” in its loyalty program.

The infringement was allegedly intentional, according to the complaint, leaving the bank no choice but to sue. The complaint says Citigroup contacted AT&T in March to express its concerns about the name, but the Dallas, Texas-based telecom provider moved forward with the program anyway. In April, it applied for the “AT&T thanks” trademark.

The lawsuit underscores the problem with trademarking everyday terms for the express use of a particular brand or product. The noun “thanks” is one of the most common words in the English language and is used freely in many contexts. According to Word Frequency Data, it’s one of the 2,000 most frequently used words out of the 450 million American-English terms analyzed by the site. It is not Citigroup’s property.

“This may come as a surprise to Citigroup, but the law does not allow one company to own the word “thanks,” said an AT&T spokesperson, in a statement. “We’re going to continue to say thanks to our customers.”

The company isn’t just upset about one word, though. The lawsuit also alleges that the font and style of the “AT&T thanks” logo are too similar to that of Citi’s “thankyou” and must be changed. What do you think?

Citigroup declined to comment on the lawsuit.