Dependent on something that is undetermined or unknown, that may or may not occur.
Possible or liable, but not certain to occur.
Not logically necessarily true or false.
Temporary.
That which falls to one in a division or apportionment among a number; a suitable share.
A quota of troops.
An event which may or may not happen; that which is unforeseen, undetermined, or dependent on something future.
Able to be omitted.