Definitions:
a faculty by which the body perceives an external stimulus; one of the faculties of sight, smell, hearing, taste, and touch

a feeling that something is the case

a sane and realistic attitude to situations and problems

a way in which an expression or a situation can be interpreted; a meaning

a property (e.g. direction of motion) distinguishing a pair of objects, quantities, effects, etc. which differ only in that each is the reverse of the other

perceive by a sense or senses

(of a machine or similar device) detect