Grasp is a synonym of Understand. Sense is a type of Understand. Sense is related to Touch. Touch is related to Embrace. 
you are likely to find Lemon in/at/on Refrigerator. Lemon is related to Bad. Bad is related to Smell. 
Grasp <--Synonym--> Understand <--IsA-- Sense <--RelatedTo--> Touch <--RelatedTo--> Embrace 
Refrigerator <--AtLocation-- Lemon <--RelatedTo--> Bad <--RelatedTo--> Smell 