Well, the term is used in a lot of industries, so there is going to be a difference depending on whether you are looking for a fixed-base operator, a fixed-base method, a fixed-base index, or a fixed-base router.
However, without using fixed base an an adjective, the definition in general could be "a foundation that does not move."
Of course a base can be a place or platform (as well as other definitions) and fixed can mean more than staying in one place... like repaired. So, it depends on the context, but that is the best generic definition you can do with only that context.
A fixed is a joint that don't move
Fixed area means that the measurement is given and does not change.
a bone that is fixed by tissue so cant move
..l..
Starter may be defined as a base structure before casting of column to keep column in fixed position and to erect form-work.
A simple definition is: a base accept a proton.
In Asia, he travelled widely, with no fixed base.
A mastaba was an ancient Egyptian tomb. The design featured a rectangular base, sloping sides, and a flat roof. It can also refer to a fixed bench, particularly of stone (Islam).
The definition for base is: A number being raised to a power of another number.
The ending of the fixed period for which a contract is valid.
A fixed jurisdictional area means that no matter how anyone tries to get out of that area, they are stuck there. This is truly a good definition of bureaucracy.
A fixed order quantity system is the arrangement in which the inventory level is continuously