The word pharmacology is derived from the Greek words pharmakon (which means drug) and logos (means a study). Pharmacology simply deals the study pharmacodynamics which means the interaction of drug with living organism.
Pharmacology can be defined as a branch of science that includes history, source, Physicochemical properties, dosage forms, methods of administration, absorption, distribution, mechanism of action, pharmacological effects, biotransformation, excretion, clinical uses, and adverse effects of drug.
For getting more knowledge about pharmacology, one should read as many books as possible. Here, You can find all sorts of pharmacology books.