Tamasic means slow or passive. Tamasic comes from the Sanskrit term, tamas, which is one of the three qualities traditionally ascribed to conditional nature in Asian philosophy.
Tamas is the principle of inertia, contraction, and passivity; rajas is the principle of action, motivation, expansion; sattva is the principle of equilibrium, harmony, and clarity.
Shown at left is a sloth, a mammal from South America that moves very slowly when it moves at all. It even digests food slowly. Sloths demonstrate many of the characteristics of tamas.
The Avataric Great Sage, Adi Da Samraj (founder of Fear-No-More Zoo), has spoken about how both fast and slow animals are able to live lives of contemplation in different ways.