on·look·er 
/ˈɑ:nˌlʊkɚ/ noun
plural on·look·ers /ˈɑ:nˌlʊkɚ/ noun [count] : a person who watches an activity or event without being involved in it
▪ Curious onlookers watched the ceremony. ▪ An onlooker noticed the disturbance. ▪ A crowd of onlookers gathered at the fire.
▪ Curious onlookers watched the ceremony. ▪ An onlooker noticed the disturbance. ▪ A crowd of onlookers gathered at the fire.
