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Thomasin

♀ Girl

Pronounced TOM-uh-sin /ˈtɑːm.ə.sɪn/Medium

Meaning: Thomasin is the medieval English feminine form of Thomas, from the Aramaic te'oma, 'twin.' It gave rise to Thomasina and to the Cornish contraction Tamsin, and it has a quiet, antique dignity of its own.Medium

In 30 seconds: A medieval English classic: Thomasin is the feminine of Thomas, 'twin' (said 'TOM-uh-sin').

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Origin MediumEnglish, Aramaic

MeaningThomasin is the medieval English feminine form of Thomas, from the Aramaic te'oma, 'twin.' It gave rise to Thomasina and to the Cornish contraction Tamsin, and it has a quiet, antique dignity of its own.

U.S. rank (2024)#13303 ↘ Falling

2024 U.S. births7 girls (0.00% of U.S. girls)

Peak year2023

Total births (all-time)≈ 60

Popularity in the U.S. · SSA data

U.S. births per year (Social Security Administration, 1880–present). Pink marker = peak year.

SSA data updated May 2026. How we source & verify this data.

History & Origin

Thomasin is the medieval English feminine of Thomas, whose root is the Aramaic te'oma, 'twin.' It was widely used from the 1300s onward, then softened into Thomasina and shortened into the Cornish Tamsin. Thomas Hardy gave it literary life in The Return of the Native. Today it reads as an antique, gently bookish choice (said 'TOM-uh-sin').

It appears only very rarely for girls in the U.S. Very rare, antique, and literary.

Did you know? Thomasin was a common English girls' name in the Middle Ages — Thomas Hardy revived it for a character in The Return of the Native, and it later gave us Thomasina and Tamsin.

Overall data confidence 55%

References — Thomasin — Medieval English feminine of Thomas; Aramaic te'oma 'twin'

Variations

ThomasinaTamsinThomasine

Nicknames

TamsinTommie

Famous Bearers

Famous bearers coming soon.

If you like Thomasin…

Tamsin— the short Cornish form of the same name

Josephine— a like feminized classic

Augustine— a like antique feminine form

Marylin— another English name

Madylin— another classic pick

Explore names like Thomasin

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Frequently Asked

What does the name Thomasin mean?

Thomasin is the feminine form of Thomas, from the Aramaic te'oma, 'twin.'

How do you pronounce Thomasin?

It's said TOM-uh-sin /ˈtɑːm.ə.sɪn/ — three syllables, stress on the first.

Is Thomasin a boy or girl name?

Thomasin is a girl's name; Thomas is its masculine source.

How popular is Thomasin?

Thomasin is a very rare name for girls in the U.S.