There’s a subtle yet significant distinction between a whole rest (AKA a semibreve rest) and a whole measure rest (whole bar rest) — the latter is the term you are looking for.
Regardless of the time signature, a whole measure rest will completely fill a measure (bar). These usually* use the same symbol as a whole rest, but are always centred horizontally within the measure (rather than aligned with the start of their duration as are other rests and notes).
Here’s an example of whole measure rests in 2/4, 3/4, and 4/4. Respectively, these have the same values as a half note (minim), a dotted half note (dotted minim), and a whole note (semibreve).
So, if you are in 4/4 you can get away with calling a whole measure rest a whole rest because it has the same value (even if this is technically incorrect because the of the spacing), but in most other time signatures this would be quiet wrong.
* When the time signature is 4/2 or larger, a whole measure rest is instead represented by the symbol for a double whole rest (breve rest) symbol.
This is because there is enough room in a measure of 4/2 for more than one whole rest.