strap-on

Short definition from Wiktionary

Adjective

1. 1
   That can be attached using one or more straps.
2. 2
   Of a booster rocket, that is mounted on the outside of a launch vehicle (typically around the first stage) to provide an additional boost at lift-off, ultimately separating after the first few minutes of ascent.

Noun

1. 1
   A strap-on booster.
2. 2
   An artificial phallus attached with a strap, usually a dildo.
3. 3
   Synonym of keytar (“keyboard supported by a strap around the neck and shoulders”).
4. 4
   Alternative form of strap-on.

Verb

1. 1
   To don a strap-on.