fetus

the word 'fetus' entered english in the late 14th century directly from latin fētus, meaning "a bringing forth, offspring, progeny." the latin term itself is derived from the pie root \dʰeh₁(i̯)-, meaning "to suckle, nurse," which also gave rise to latin fēmina ("woman") and fēlāre ("to suck"). the semantic journey is from the general concept of "bringing forth" and "that which is brought forth" to its specific modern biological meaning of a later-stage developing mammalian embryo. this specialization in meaning occurred as scientific terminology became more precise, distinguishing it from earlier stages of development.

the entire word 'fetus' is treated as a simplex unit. it is a direct borrowing from latin, where 'fētus' meant "offspring, bringing forth, pregnancy." its functional role is as a noun-forming root.