A subsense is a meaning of a word that is not the main meaning, but is related to it.
Subsenses help people understand all the different ways a word can be used.
Examples:
The word 'light' has many subsenses, like 'not heavy' and 'gives off light'.
In the word 'book', the subsense 'to reserve' is not the main meaning.
The subsense of 'fast' as 'quick' is different from the subsense of 'fast' as 'not moving'.
The subsense of 'dog' as 'a friend' is funny.
The subsense of 'big' as 'important' is very interesting.
The subsense of 'run' as 'to operate' is easy to remember.