1. Having the nature of an improvisation

Encyclopedia: Improvisational

• open sandwich
• open season
• open secret
• open sesame
• open shop
• open sight
• open society
• Open University
• open up
• open weave
• open-air
• open-air market
• open-air marketplace
• open-and-shut
• open-angle glaucoma
• open-class word
• open-collared
• open-door policy
• open-end credit
• open-end fund
• open-end investment company
• workflow
• workforce
• workhorse
• workhouse