Rex
Masculine · Latin roots · “King (Latin)”
Rex is overwhelmingly a boys’ name — 60,449 boys against 141 girls since 1880.
Rex is the Latin word for king, worn as a name with no translation needed — one syllable, three letters, and nothing hidden in the spelling. It was the title of the kings of early Rome, and it survived in Roman ritual language long after Rome had stopped having kings. In American use it rose through the middle of the last century and has been easing back since, so it is familiar to the ear without being crowded.
How old is the name Rex?
Rex was already in use when US birth records began in 1880 — it is at least 145 years old. The typical Rex alive today was born around 1954, making them about 71 years old. About 36,500 people named Rex are estimated to be alive in the US today.
When was the name Rex most popular?
Rex peaked in 1951, reaching #170 nationally. Today it ranks #859, 689 places below that high. See the whole 1951 chart.
Where it comes from
From regere (Latin, to rule) to Rex
The story of Rex
Rex is the Latin noun for king, from the verb regere, to rule, and it belongs to a very old word family: Sanskrit rājan and Irish rí are its cousins. Rome used it for its earliest kings, then kept it in legal and priestly formulas — the rex sacrorum held a religious office long after the monarchy was gone — and it stayed alive in Latin mottoes and inscriptions through the Middle Ages. It began appearing as an English given name in the nineteenth century, alongside the same taste for plain Latin words that gave us Regina, and it doubled as a short form of Reginald and Rexford. American records show it in continuous use from the earliest years they cover, with its strongest showing around the middle of the twentieth century.
Meaning
King (Latin)
Latin rex, genitive regis, from regere, to rule.
How the name formed
- regereLatin, to rule
- rexLatin, king
- Rex
Related forms: Rex · Rex · Rex · Rey
Pronouncing Rex
REKS
One syllable, said exactly as written. No competing pronunciations in English, and it survives most other languages unchanged.
Nicknames for Rex
Moderate
What the data says
146 years of official birth records
The long climb, and where it stands now
The same years in position rather than babies
- First recorded
- 1880
- Most boys named
- 19511,503 — the highest on record
- Peak rank
- #170reached in 1951
- Change vs 2022
- −26.1%281 in 2025, from 380
Rank is a position, a count is a headcount, and they move independently — a name can hold its rank while the number of babies behind it falls. Source: U.S. Social Security Administration.
Rex in other languages
The same name elsewhere
- Rex in Latin — same name
- Rex in German — same name
- Rex in Dutch — same name
- Rey in Spanish — related form
Strongest US states over the last decade: California, Texas, Florida.
Rexs among us
people named Rex are estimated to be alive in the US today
About 1 boy in 6,079 born in 2025 was named Rex
Estimated from SSA birth records and published actuarial life tables. Method
Is it right for you
What happens to a name after it peaks
The Merle test
Every popular name lives one long story — a climb, a peak, a slow settling back. Rex's later chapters haven't been written yet, so we borrowed them: Merle climbed just as high around 1918, and its whole arc is on record. Line the two peaks up, and Merle's path sketches the road Rex is walking now.
Rex sits in the calm middle of the cycle — neither chasing a wave nor sliding off one. Middle-of-the-cycle names age slowly and predictably.
A scored estimate from 146 years of naming cycles — not a prophecy. Great names outlive statistics. How this is scored
Where Rex is headed
Rex should hold steady through 2030 — the curve is flat, and flat curves are the most predictable kind.
High confidence — fitted on official counts through 2025.
A damped-trend projection of the official birth data — a sketch of momentum, not a promise. Every name's forecast, ranked.
Rex beside its neighbors
The names ranked closest to Rex in 2025, in babies rather than position — the bars are to scale.
US boys given each name in 2025.
The trade-off
- Three letters, one syllable, spelled the way it sounds — almost impossible to misspell or mispronounce, in English or out of it.
- A real Latin word with a meaning any reader can state, rather than an origin that has to be looked up.
- Needs no nickname to be usable, and works equally as a full name or as the short form of Reginald or Rexford.
- An unbroken record in American use spanning well over a century, including a strong mid-century run, so it reads as established rather than new.
- Recognizable across German, Dutch and other European use without any change in spelling.
- Rex has been a standard dog's name in English for generations, and someone will make that joke. It fades fast, but it does not disappear entirely.
- Tyrannosaurus rex means tyrant lizard king, and every child in a classroom knows it. Expect dinosaur associations in the early years — which many boys enjoy rather than mind.
- A name meaning king is a bold thing to say out loud at an introduction. Some families like the directness; others prefer their Latin a little less literal.
- There is no long formal version to fall back on, so Rex is what he has at every age and in every setting. It also means he is unlikely to share it with anyone in his year.
Nobody names a baby alone.
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What they receive
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Rex
Masculine · Latin roots · #859 in the U.S.
Frequently asked
- How many Rexs are there in the world?
- No country counts the world's names, so there is no worldwide figure — anyone quoting one is estimating. About 36,500 people named Rex are estimated to be alive in the US today.
- How popular is the name Rex in 2025?
- Rex ranks #859 among US boy names in 2025, with 281 babies given the name.
- How rare is the name Rex?
- About 1 in every 6,079 US boys born in 2025 was named Rex — 281 in all.
- Will my child share the name Rex with classmates?
- Rex will almost certainly be the only one in school.
Ranked beside Rex
Names sitting at a similar level of popularity right now.
Avyaan#858 · Aslan#860 · Eddie#860 · Evren#857 · Lance#862 · Zechariah#855 · Stanley#863 · Santana#855
Looking for what else is popular rather than what resembles Rex? See the current top 100.
Choosing between Rex and another name?
See them side by side — full stats, history and a gentle verdict.
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Which one would you pick?
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US figures from the Social Security Administration. 1880–2025. Data & methodology
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