Definition of Kiss

Prof of Economics : Kiss is that thing for which the demand is always higher than the supply.
 
Prof. of Accountancy : Kiss is a credit because it is profitable when returned.
 
Prof. of Algebra : Kiss is infinity because two divided by nothing

Prof. of Geometry : Kiss is the shortest distance between two lips
 
Prof. of Physics : Kiss is the contraction of mouth due to the expansion of the heart.
 
Prof. of Chemistry : Kiss is the reaction of the interaction between two hearts.
 
Prof. of Zoology : Kiss is the interchange of salivary bacteria
 
Prof. of Physiology : Kiss is the juxtaposition of two orbicularisoris muscles in the state of contraction.
 
Prof. of Dentistry : Kiss is infectious and antiseptic.
 
Prof. of Statistics : Kiss is an event whose probability depends on the vital statistics of 36-24-36.
 
Prof. of Philosophy : Kiss is the persecution for the child, ecstasy for the youth and homage for the old.
 
Prof. of English : Kiss is a noun that is used as a conjunction; it is more common than proper; it is spoken in the plural and it is applicable to all.
 
Prof. of Architecture : Kiss is a process which builds a solid bond between the two dynamic objects.

Prof. of Comp.Science : What is a kiss? It seems to be an undefined variable.