Does anyone know of a source that would indicate the first (give or take) usage of the word "baby" to mean fetus or any synonym of fetus? Every reference I've found thus far points to the usual meanings, but none indicate this particular usage. Even so, "fetus" is listed as an alternate definition in the few dictionaries I've checked.

Thanks in advance for any feedback!

  • 4
    I'm not sure if the word "baby" ever means "fetus", any more than the word "person" means "adult". Rather, it's that fetuses are considered to be babies, or conceptualized as babies, in the usual sense of that word. ("Unborn infant" is attested since at least the 1600s.)
    – ruakh
    Dec 12, 2015 at 5:30
  • 2
    The synonymous expression "unborn baby" was used as early as 1820, if that's any help.
    – Mari-Lou A
    Dec 12, 2015 at 7:58
  • 2
    However, the expression "unborn Infant" is older, the link is from a book dated 1716
    – Mari-Lou A
    Dec 12, 2015 at 8:05
  • I've only seen ruakh's comment, so I've checked and found a 1655 reference from a book titled Anabaptism routed
    – Mari-Lou A
    Dec 12, 2015 at 8:32
  • @Mari-LouA Great finds. Why don't you post them as an answer?
    – A.P.
    Dec 12, 2015 at 9:30

3 Answers 3


Fetus was used to refer to a newborn child also in Latin:

  • In Latin, fetus sometimes was transferred figuratively to the newborn creature itself, or used in a sense of "offspring, brood" (as in Horace's "Germania quos horrida parturit Fetus").

The Pregnancy Terms Glossary of Medical Terminology defines:

Fetus as:

  • Medical term for the baby before it is born, ie when still in the uterus.

the AHD and the Collins Dictionary give one definition of baby as:

  • An unborn child; a fetus.

Ngram show usage of the expression baby fetus from the 60's.

  • The term fetus can also be spelled as foetus I think that's BrEng spelling. Well worth seeing if there's any difference in the Ngram thingy.
    – Mari-Lou A
    Dec 12, 2015 at 7:49
  • No evidence for 'baby foetus' on Ngram.
    – user66974
    Dec 12, 2015 at 7:52
  • Fetus vs foetus in BrE : books.google.com/ngrams/… - Fetus vs Foetus in AmE: books.google.com/ngrams/… - no 'baby foetus' in BrE.
    – user66974
    Dec 12, 2015 at 7:55

No, I don't think this has ever been done. Fetus is an exact development stage. Baby is the generic catch all term. Thus you have the implication arrow pointing in the wrong direction. Fetus implies baby. But "baby" might mean a 5 year old boy or my fluffy eared Beagle.

  • I agree. Pro-life campaigners seem to regard a zygote (unimplanted fertilised egg), let alone an embryo or foetus, as a child deserving of protection. I think "baby" is the overall term for all stages up to toddler at least.
    – BoldBen
    May 21, 2019 at 9:06

According to Online Etymology Dictionary, baby comes from babe:

late 14c., short for baban (early 13c.), which probably is imitative of baby talk (see babble), however in many languages the cognate word means "old woman" (compare Russian babushka "grandmother," from baba "peasant woman").

Crist crid in cradil, "moder, baba!" [John Audelay, c. 1426]

Now mostly superseded by its diminutive form baby. Used figuratively for "a childish person" from 1520s. Meaning "attractive young woman" is 1915, college slang. Babe in the woods is from 1795.

The word fetus is rather a medical term like embryo. Its usage picked up sharply around '60s and '70s when the abortion rights movement peaked as the linked Ngram Viewer shows.

the developing young in the uterus, specifically the unborn offspring in the postembryonic period, which in humans is from the third month after fertilization until birth

[Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition]

Unborn baby and unborn child could be synonymous with fetus. Depending on context, baby could also mean a human fetus as defined in Dictionary.Com. However, it would be very difficult to pinpoint when baby started to mean a human fetus as baby has a lot of different meanings including attractive young woman.

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