Choose the adjective tentative to describe something you are unsure or hesitant about. On Monday, you can make tentative plans for the weekend, but it's too early to commit to one party or another.
Tentative, from the Latin tentātīvus "testing, trying," always describes something that is uncertain. If you make a tentative appointment, write it down in pencil, not pen, because it might have to be changed. Here the opposite of tentative is definite or set. If someone gives you a tentative smile or nod, the person feels hesitant or unsure about something. In this case, its opposite is confident.