Anomia, a symptom of aphasia.

Edit: further reading on expressive aphasia loops back to disfluency mentioned in tranquilled's answer.

Anomia, a symptom of aphasia:

Anomic aphasia (also known as dysnomia, nominal aphasia, and amnesic aphasia) is a mild, fluent type of aphasia where individuals have word retrieval failures and cannot express the words they want to say (particularly nouns and verbs). Anomia is a deficit of expressive language. [...] Individuals with aphasia who display anomia can often describe an object in detail and maybe even use hand gestures to demonstrate how the object is used, but cannot find the appropriate word to name the object.

Further reading on expressive aphasia loops back to "disfluency", as mentioned in Tranquilled's answer.

Anomia, a symptom of aphasia.

Anomia, a symptom of aphasia.

Edit: further reading on expressive aphasia loops back to disfluency mentioned in tranquilled's answer.