Cohesion has different meanings depending on the context. Here are some definitions from the search results:

• In linguistics, cohesion refers to the grammatical and lexical linking within a text or sentence that holds a text together and gives it meaning. It is related to the broader concept of coherence).
• In general, cohesion means sticking together tightly, especially unity. It can describe particles that are the same and tend to stick together, such as water molecules.
• In physics, cohesion refers to the intermolecular attractive force acting between two adjacent portions of a substance, particularly of a solid or liquid. It is this force that holds a piece of matter together. Intermolecular forces act also between two dissimilar substances in contact, a phenomenon called adhesion.

Therefore, cohesion can refer to the linking of words and sentences in a text, the unity of a group or substance, or the attractive force between particles of the same substance.