at·tach / əˈtach/ • v. [tr.] fasten; join: he made certain that the trailer was securely attached to the van. ∎  fasten (a related document) to another: I attach a copy of the memo for your information. ∎  include (a condition) as part of an agreement: the Commission can attach appropriate conditions to the operation of the agreement. ∎  used to indicate that someone regards something as important or valuable: he doesn't attach too much importance to radical ideas. ∎  [intr.] (attach to) used to indicate someone regards something as important or valuable: in South Korea enormous importance is attached to respect for the dead. ∎  (attach oneself to) join (someone or something) without being invited: they were all too ready to attach themselves to you for the whole day. ∎  (usu. be attached) appoint (someone) for special or temporary duties: I was attached to another department. ∎  Law seize (a person's property) by legal authority: the court attached his wages for child support.DERIVATIVES: at·tach·a·ble adj.

attach To make a device available for use by a system. On simple systems this may be achieved by simply engaging the appropriate plug and socket of the interface and putting the device into a state of readiness. In more complex systems it is often necessary to make the operating system aware of the type of device and the address of the connector to which it is attached. It is also necessary to ensure that the operating system has available the appropriate utility program for that device. In some designs the operating system can itself determine the type and address of all the peripherals that are electrically connected. See also install.

attach seize, arrest XIV; fasten, join XV. — OF. atachier (mod. attacher), alt., by prefix-substitution, of estachier fasten, fix, f. Gmc. *stak- STAKE1.
So attachment XIV.