A usually secretive or illicit sexual relationship

• A sense of concern with and curiosity about someone or something
• A connection of inclusion or containment
• Inclusion; entanglement
• Sharing the activities of a group

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun COLLOCATIONS FROM OTHER ENTRIES active participation/involvement (= in an activity or event ) ▪ Active participation in community life is important in small towns and villages. ▪ The school encourages the active involvement of parents. deny any involvement ...

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
1706, from involve + -ment .

Wikipedia Word definitions in Wikipedia