One view of Semantics is that it is about the relationship between words and reality. One problem with this is that it possible to construct a perfectly grammatical sentence using perfectly ordinary words and make no sense at all; Chomsky’s famous Colorless green ideas sentence seems to have no connection with reality.
In Through the Looking Glass, Alice is surprised that her head becomes filled with ideas when reading the nonsense poem Jabberwocky. How can nonsense words fill your head with ideas? It seems that our minds work in creative and imaginative ways to make sense of the words we hear.
As Humpty Dumpty suggests, we creatively and imaginatively control words to mean different things in different situations. Take a simple sentence like 1 below.
1. I have eaten an apple.
Sentence 1 could suggest different things depending on the situation. If I ask you if you need to eat soon and you reply with 1, it could mean you are not very hungry or it could mean that you actually are a bit (or even very) hungry. It depends how you say it and the body language you use.
If I ask you Why are you looking for your toothbrush? and you reply with 1, it would probably mean that you are worried that your teeth are not very clean.
If I tell you The basket of fruit on the table has been poisoned and you reply with 1, it could be taken as an alarm suggesting Help me get to the hospital as quickly as possible. Interestingly, it would still carry this meaning even if there had been no apples in the basket of fruit and that you actually ate some other kind of fruit. In other words, even if 1 is not true, it still carries its important meaning.