What is mean by atypical febrile convulsion

Fever is not dangerous; rather it is one of the protective mechanism of your body against any infection or inflammation. Yes, high rise of body temperature more than 105 degree F can result febrile convulsion, muscles rigidity or more heart beat, and still more high temperature may cause brain hemorrhage or organ failure, but in practically temperature from 100 F to 103 F will not result any problem (except in the case of a child who has a P/H of febrile convulsion record).

A convulsion is an uncontrolled movement of muscles.

'Post-' means 'after'. 'Febrile' means 'pertaining to a fever'. Therefore 'post-febrile' means 'pertaining to the period after a fever'.

The febrile agglutinins test is used to confirm the diagonsis of certain infectious diseases that stimulate the body to produce febrile agglutinins.