Tentative is an adjective that describe an action that you feel uncertain of , an action that you feel unsure of its correctness; nonetheless, it's done to see what will happen

Dictionary.com says 1. of the nature of or made or done as a trial, experiment, or attempt; experimental: a tentative report on her findings. 2. unsure; uncertain; not definite or positive; hesitant: a tentative smile on his face (maybe he's nervous so he's trying to smile but you can see he's nervous) I usually use this word in case 2. for example: "I tentatively accept your invitation" = i'm not sure if i will be able to come but I would like to, or things might change. He was tentative about it = he was a bit unsure.

Please take a look here: http://www.linguee.com/english-russian/search?source=auto&query=tentative

Dependent on something else or a number of factors. Something you expect to occur in the future but at present may change or not happen at all and thus doesn't inspire much certainty. Not set in stone. "We have tentative plans to visit her if the weather permits."