What does Rex mean?
Directly from the Latin noun 'rex', meaning 'king' — the same root behind 'regal' and 'royal'. One of the few names that literally means 'king' with no ambiguity.
What does Felix mean?
The Latin word felix, “happy” or “lucky.”
Rex vs Felix
Which is more popular?
Felix is more popular than Rex today: about 2,064 US babies were given the name Felix in 2025, compared with 281 named Rex.
| Rex | Felix | |
|---|---|---|
| Meaning | king | Happy, fortunate |
| Origin | latin | Latin |
| Gender | Boy | Boy |
| Pronunciation | reks | FEE-liks |
| Syllables | 1 | 2 |
| First appeared | 1880 | 1880 |
| Peak year | 1951 (1,503) | 2024 (2,090) |
| In 2025 | 281 | 2,064 |
| Trend | Steady | Near its peak |
Popularity over time, 1880–2025
Rex
Felix
Source: US Social Security Administration.
Births by decade
| Decade | Rex | Felix |
|---|---|---|
| 2020s | 2,106 | 11,654 |
| 2010s | 3,945 | 13,335 |
| 2000s | 2,048 | 7,580 |
| 1990s | 1,740 | 6,294 |
| 1980s | 2,532 | 5,306 |
| 1970s | 3,359 | 5,515 |
| 1960s | 8,735 | 5,749 |
| 1950s | 13,499 | 5,759 |
| 1940s | 6,671 | 4,315 |
| 1930s | 5,949 | 4,199 |
| 1920s | 5,627 | 6,000 |
| 1910s | 3,253 | 4,928 |
| 1900s | 497 | 1,108 |
| 1890s | 305 | 903 |
| 1880s | 183 | 863 |
Frequently asked questions
Is Rex or Felix more popular?
Felix is more popular than Rex today: about 2,064 US babies were given the name Felix in 2025, compared with 281 named Rex.
What is the difference between Rex and Felix?
Rex means king (latin origin), while Felix means Happy, fortunate (Latin origin).
Which name is older, Rex or Felix?
In US records, Rex first appears in 1880 and Felix in 1880, so Rex has the longer recorded history.