Final answer:
Nonverbal communication refers to the use of gestures in speech that have specific meanings, often culturally defined, such as a thumbs up for approval or different meanings in other contexts.
Step-by-step explanation:
The term for gestures in speech that have meanings, such as a thumbs up, is nonverbal communication. These gestures are symbolic and often culturally specific. For instance, while a thumbs up is seen as positive in the United States, it can be an offensive gesture in countries like Russia and Australia. Gestures like a wave of the hand or a wink can convey a spectrum of messages from greetings to expressing secretiveness or attraction. Understanding these gestures is crucial as they complement spoken language and can convey emotions and intentions beyond words.