n. pl. fe·tus·es
1. The unborn young of a viviparous vertebrate having a basic structural resemblance to the adult animal.
2. In humans, the unborn young from the end of the eighth week after conception to the moment of birth, as distinguished from the earlier embryo.
[Middle English, from Latin fētus, offspring; see dhē(i)- in the Appendix of Indo-European roots.]
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Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.