To cause fertilised eggs to lose viability, by killing the developing embryo within through shaking, piercing, freezing or oiling, without breaking the shell
To make addle; to grow addle; to muddle; as, he addled his brain. "Their eggs were addled." Cowper
If something addles someone's mind or brain, they become confused and unable to think properly. I suppose the shock had addled his poor old brain. = befuddle. to confuse someone so they cannot think properly addle sb's brains/wits