Dear Aspirant,

Hope you are doing fine! The term is used in Chemistry which means free radical is an atom, molecule, or ion that has at least one unpaired valence electron or it is a oxygen containing molecule with uneven number of electrons. National cancer Institute has its own term of free radical which is known as  a type of unstable molecule that is made during normal cell metabolism (chemical changes that take place in a cell) which causes cancer.

nucleophil  - a nucleophile is efficient in electrons it forms bonds by donating an electron pair. All molecules and ions with a free pair of electrons or at least one pi bond can act as nucleophiles.

So free radicals which are deficient in electrons can act as electrophile by accepting electron from nucleophile.

hope this information is helpful  :)