pro-drop language
Definition - A language in which speakers are almost always allowed to leave out the sentence's subject.
Note: As opposed to non-pro-drop languages where (for the most part) the sentence's subject must be present.

Example -
For the most part, English is a non pro-drop language; however, pronouns can be dropped from commands (e.g. "Come here!")

Etymology -
The term pro-drop (which is short for pronoun dropping) derives from Noam Chomsky's 1981 Lectures on Government and Binding.

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