Meaning: Central or essential part:
* The core of the problem lies in their lack of communication.
* Her core beliefs are deeply rooted in her upbringing.
* The core of the apple was rotten.
Meaning: Center of something:
* The Earth's core is extremely hot and dense.
* The teacher emphasized the core concepts of the lesson.
* The new building will be constructed around a steel core.
Meaning: Group of people who are central to an organization:
* The core team is responsible for launching the product.
* The core membership of the club has been active for years.
* He joined the core of the political party and began campaigning.
Meaning: Muscles in the center of the body:
* Strengthening your core muscles can improve your posture and balance.
* She did some core exercises to strengthen her abdominal muscles.
* The core muscles help stabilize your spine.
These are just a few examples, and the meaning of "core" will depend on the context of the sentence.