As for the etymology the term enemy is derived from Latin language for 'bad friend' (Latin: inimicus). Enemy is a strong word, and emotions associated with the enemy would include anger, hatred, frustration, envy, jealousy, fear, distrust, and possibly grudging respect . As a political concept, an enemy is likely to be met with hate, violence, battle and war. The opposite of an enemy is a friend or ally.
diffusion. 1. The process of rapid random movement of the particles of a liquid or gas which eventually form a uniform mixture. 2. The mixing of substances due to the motion of their particles.
Diffusion is the net movement of material from an area of high concentration to an area with lower concentration. The difference of concentration between the two areas is often termed as the concentration gradient, and diffusion will continue until this gradient has been eliminated.