If you are referring to analog tape:

Full track - single track recorded across the full width of the tape (rare)

Half track - two tacks on a tape, each occupying half the width of the tape

1/4 track - (domestic standard) 4 tracks on a tape, but only two in each direction (turn the tape over to access the other two)

four track - four tracks across the width of the tape, all usable at once.

n-track - ditto for n tracks.

Note these definitions do not say anything about the physical width of the tape.

thank you