Talking about probability in English

There are many ways of saying that something will probably or possibly happen.
Probable
bound to = certain: "They are bound to succeed!"sure to = certain: "He is sure to win the championship."likely to = probable: "We are likely to win the contract."definite = sure: "He's a definite frontrunner for the job!"probable: "It's probable that we will be on holiday around then."likely: "An election is likely next year."will definitely happen: "There will definitely be a storm later."will probably happen: "They will probably take on more staff."
Possible
may: "We may be able to help you."might: "There might be a holiday next month – I'm not sure."could: "There could be a bug in the system."… is possible: "Do you think he will resign?" "Yes, that's possible."… is unlikely: "It's unlikely that she will move."will possibly: "She'll possibly tell us tomorrow."probably won't: "They probably won't hear until next week."definitely won't: "I definitely won't go to the party."… is highly unlikely: "It's highly unlikely that the company will expand."
Note: Be careful of the word order."Definitely" and "probably" come after "will" (in positive sentences) and before "won't" in negative sentences.
Variations
You can add words to alter the strength of probability:
highly likely / unlikely (= very likely / unlikely)quite likely / probable / possible (= more likely, probable or possible)
could possibly / probably
most definitely won't (= even more unlikely)