See plug something ↔ in for more
plug-in
ˈplug-in1
adjective [only before noun]
able to be connected to the electricity supply, or to another piece of electrical equipment:
a plug-in microphone
plug-in2
, plug‧in /ˈplʌɡɪn/ noun [countable] technical
a piece of computer software that can be used in addition to existing software in order to make particular programs work properly
| I |
adjective [only before noun]able to be connected to the electricity supply, or to another piece of electrical equipment:
| II |
, plug‧in /ˈplʌɡɪn/ noun [countable] technicala piece of computer software that can be used in addition to existing software in order to make particular programs work properly