What does Semper Fi mean in English? Sullivan's tattoo in Boots explained

13 October 2025, 17:35 | Updated: 14 October 2025, 15:08

By Sam Prance

A huge Boots storyline revolves around Sullivan's Semper Fi tattoo but what does it mean? Here's the English translation.

Netflix's new series Boots is filled with twists and turns but it may also leave you wondering what 'semper fi' means.

As soon as Boots came out on Netflix, it immediately transfixed viewers. Inspired by Greg Cope White's best-selling autobiography The Pink Marine, the show explores what it's like to be secretly gay in the marines in the 1990s. The Don't Ask Don't Tell law was in full effect and it was against the law to be openly homosexual in the US military.

One key Boots storyline involves a tattoo of the Latin phrase 'semper fi'...so what does 'semper fi' mean in English?

• Read more: Is Sullivan gay in Boots on Netflix? His secret past explained

Watch Netflix's Boots trailer

What does Semper Fi mean?

'Semper fi' is short for the popular Latin phrase 'semper fidelis'. 'Semper fidelis' literally translates to "always faithful" or "always loyal" in English and it has been used as the official motto of the United States Marine Corps since 1883.
Before 'semper fidelis', 'fortitudine' (with courage) and 'per mare, per terram' (by sea, by land) were used.

'Semper fi' takes on a huge role in Boots as we learn that Sergeant Liam Robert Sullivan has the phrase tattooed on his chest. In the show, Sullivan is questioned about the sexuality of a former officer named Major Wilkinson who served together with Sullivan during his time in Guam. We later learn that Wilkinson has the same tattoo.

• Read more: Boots season 2: Release date, cast, book spoilers and news about the Netflix show

Is the Semper Fi tattoo common in the military?

As 'semper fidelis' is the official marines motto in the US, it's not uncommon for marines to have the phrase 'semper fi' tattooed on them. However, the placement of the tattoo varies from person to person as does the style.

In Boots, Sullivan and Wilkinson both have the tattoo in the same font on the left side of their chests.

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