Based on the results of field-dependent dielectric and magnetic measurements, we observe several interesting behaviors and phase transitions in this geometrically frustrated spinel system CdCr2S4. (1) A glassy dipolar state occurs near T-C similar to 85 K, which is induced by the onset of ferromagnetic ordering. (2) A ferroelectric ordering occurs near T-p similar to 56 K, which is enhanced by externally applying electric field. (3) Both the magnitude and step-up temperature of dielectric constant (epsilon(')) near T-C are suppressed by an electric field yet are increased by the magnetic field. (4) Both electric and magnetic fields colossally enhance the magnitude of dielectric constant (epsilon(')) near T-p. (5) A clear dip of magnetization under various electric fields is observed near T-p indicating the different spin-dipole interactions near T-C and T-p. Attempts are made to analyze these field-dependent properties by considering the strong spin-lattice coupling and exchange striction effect in this novel multiferroic material.