adjective / noun

premature

pree-muh-CHOOR/ˌpriːməˈtʃʊr/

Occurring earlier than the expected or appropriate time.

The sprinter makes a premature start while the official's pistol remains lowered.

A sprinter launches from his starting blocks while his competitor remains in the set position and the race official is still holding the starting pistol lowered, making the too-early start visible.

Etymology

The combination originally described fruit as early ripe. Ripening ahead of the usual time provides the image for anything happening before its proper time.

In context

Rood & Riddle9:14

so red bag deliveries are a big one so if there's basically premature early separation of the placental membranes

A Foal’s First 24 Hours and Beyond with Dr Kate Christie

More examples

Without more evidence, that conclusion seems premature.
Their premature baby needs extra care before coming home.
Regular maintenance helps prevent premature wear on the engine.

Forms

premature · prematures · more premature · most premature

prematurely adverb — Before the proper or expected time.

prematurity noun — The state of occurring too early.

Similar words

early: May simply precede the usual time, without implying inappropriateness.
untimely: Emphasizes bad timing, which need not mean too early.
hasty: Describes actions rushed without enough thought or preparation.