A Houston museum issued a public apology for using a subject line that could be construed as racially offensive, the Houston Chronicle reported.

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The Houston Museum of Natural Science used the term “Party with spooks” in the subject line of its bi-weekly electronic newsletter, the newspaper reported.

While the word "spook" is a synonym for "ghost," it is also a derogatory slur for black Americans.

"It's a tie to our annual Halloween party, which we've been doing for 10 years," museum president Joel Bartsch told the Chronicle. "The word was meant to be a riff on the word spooky. That was the intention."

Bartsch said that when his employees saw the subject line, they addressed it by sending an explanation, the newspaper reported.

"Internal eyes noticed the subject line directly after it was sent,” Bartsch told the newspaper.

The explanation reads:

"HMNS is committed to diversity and inclusion. We deeply regret that the subject line in this newsletter included a word with an offensive connotation, and sincerely apologize to everyone who received it. We are revisiting our internal policies and editorial review procedures to ensure this does not happen again."