【Join】 , 【conjoin】 ,  【combine】 ,  【unite】 ,  【connect】 ,  【link】 ,  【associate】 ,  【relate】  are comparable when meaning to attach or fasten one thing to another or several things to each other or to become so attached or fastened.

【Join】 stresses the bringing or coming together into contact or conjunction of two or more clearly discrete things.

【Join】 is the specific term when one becomes a member of a group or enters into the company of others as an equal.

【Conjoin】 usually emphasizes both the separateness and distinctness of the items to be joined and the unity that results from their being joined.

【Combine】  in this relation (see also  【UNITE】 2 ) adds to  【join】 the implications of a mingling or blending and may stress more heavily the idea of a common purpose or end; it is therefore used of two or more, often immaterial, things that may lose or seem to lose their identities and become merged in each other.

【Unite】 , like  【combine】 , implies a blending that effects the loss of individual identity of the elements, but, like  【conjoin】 , 【unite】 stresses the singleness of the result.

【Connect】  implies a loose or, at least, an obvious attachment of things to each other and the preservation not only of each thing’s identity but also of the evidence of its physical or logical separateness; in this way it is distinguishable from  【join】  when physical attachment is implied; thus, a wall is built up of bricks joined, rather than connected, together by cement but a chain is made by connecting a succession of steel links; often  【connect】 implies an intervening element or medium which permits joint movement and intercommunication.

When the idea of logical attachment is uppermost,  【connect】 usually implies that the ideas, events, or things whether material or immaterial have a bearing on each other (as of cause and effect, generic likeness, or reference to the same person or thing).

【Connect】 , especially in the passive, is preferable to  【join】 when used in reference to organizations or groups and looseness of attachment, impermanence, or subordination is implied.

【Link】 , with its underlying reference to one of the parts of a chain, is usually more emphatic than  【connect】  in implying firmness of attachment; it is therefore the more precise word when one wishes to preserve the basic implications of  【connect】  and yet to avoid its common connotations of a weak or severable attachment; thus, to  【link】 a person with a crime is, by implication, to have ample evidence of his involvement with it.

【Associate】 primarily implies a joining with another usually in an amiable relationship and on terms of equality. In its extended use as referred to things, the implication of companionship on equal terms gives way to the implication of a connection in logic or in thought which comes naturally or involuntarily to the mind of the observer either because the things traditionally go together, or naturally or rightfully belong together, or for some reason have come to be linked together in one’s thoughts.

【Relate】  implies a connection, or an attempt to show a connection, between two or more persons or things. In reference to persons it implies a connection through a common ancestor or through marriage <John and James are remotely related to each other>  In reference to things or to persons objectively regarded, it implies that each has some bearing on the other and often indicates the existence of a real or presumed logical connection.