piggyback

Short definition from Wiktionary

Adjective

1. 1
   On somebody's back or shoulders.
2. 2
   Pertaining to transportation of goods where one transportation unit is carried on the back of something else. For example, a truck on a train.
3. 3
   Attached or appended to something larger or more important.

Adverb

1. 1
   On somebody's back or shoulders.

Verb

1. 1
   To carry (someone) on the back or shoulders.
2. 2
   To ride on someone's back or shoulders.
3. 3
   To attach or append something to another (usually larger) object or event.
4. 4
   To obtain a wireless internet connection by bringing one's own computer within the range of another's wireless connection without that subscriber's permission or knowledge.
5. 5
   To utilize "last-mile" wiring rented from a larger owner ISP by a smaller ISP.
6. 6
   To transport (a lorry/truck) on a flatbed railway wagon.
7. 7
   To enter a secured area at the same time along with (someone having authorized access); to tailgate.

Noun

1. 1
   A ride on somebody's back or shoulders.
2. 2
   An act or instance of piggybacking.
3. 3
   The connection of one intravenous drip to another.