What does atomic radius and ionic radius really mean to you?

Atomic radius means the size of the atom i.e. the distance from the centre of the nucleus of the atom to the outermost shell of electrons. In the case of non-metals, atomic radius is called covalent radius. It is defined as one-half of the distance between the centres of the nuclei of two similar atoms bonded by a single covalent bond. In the case of metals, atomic radius is called metallic radius. It is defined as one-half of the distance between the two adjacent atoms in the crystal lattice.
Ionic radius means the size of the ions. It may be defined as the effective distance from the nucleus of the ion to the point to which it has an influence in the ionic bond. The size of the cation is always smaller as compared to that of the parent atom. The size of the anion is always larger as compared to that of the parent atom.