These verbs apply to things that are brought or fastened together. Connect is used of things that come into contact at some point while clearly remaining separate. Things may be directly connected or, as is often the case, connected by some intervening means or agency: connecting rooms in a hotel, with a bath between them; two large land masses connected by an isthmus. Connect also may suggest a contact that results in the transfer of power from a source to a receiver. One connects a radio by inserting its plug into an electrical outlet. A switchboard operator can connect two people over the telephone by connecting the proper electric circuits. A boxer who hits his opponent solidly is said to connect . Attach is applied to things that are or that may be connected securely but that retain their separate identities and are separable. Attaching implies the fastening on of a part to a whole, of a lesser thing to a greater, or of something movable to something fixed. Hence one may attach a flash-gun to a camera, a pin to a dress, or a fire-hose to a hydrant. A barnacle attaches itself to a ship. A door is attached to the doorpost by hinges. Applied to persons, connect may suggest an indefinite relationship, while attach may imply a specific but temporary association.

• He is connected with the government in some capacity; An attaché is a person officially attached to a diplomatic mission.

Link suggests a connection like that of loops in a chain. When things brought directly together are linked , they are interlocked: to link arms. But things not in contact may also be linked by something that forms a bond between them. A linking verb is one that serves to connect the subject of a sentence with the predicate. Link may also mean to find or point out a connection between things: to link cigarette smoking to cancer. Couple stresses pairing. To couple is to connect two things, often by means of a linking device: to couple railway vans. To couple electric circuits is to connect them magnetically or directly, permitting transfer or power from one to the other.

Join and unite are applied to things that come together closely or combine. Join stresses the previous, and possibly the future, separateness of the parts, while unite emphasizes the new whole that is formed. Two or more things may join through mutual action or adjacent location, or may be joined by being fitted or linked together.

• The two groups joined forces against a common enemy; join hands and form a circle.

Also, a lesser thing may join a greater or a single person may join a group, each becoming a part of the whole: to join a club.

• Join us at our table; The Murrumbidgee and the Darling rivers join the Murray.

To unite is to join together so as to form one integral whole. Two or more things that unite give up all or part of their separateness in order to exist or act as one: to unite two ingredients in a mixture or compound; The states united to form a nation.

All these words can be applied to inter-personal relationships. Attach suggests personal ties of affection: He grew attached to her. Link can imply a coupling: Their names were linked in the gossip columns. Couple can mean to copulate. Join and unite are applied to marriage, while connect indicates a looser, much less intimate association: to join a man and a woman in holy matrimony.

• They were united in marriage; Their families are now connected by marriage.