Although I easily guessed this word from the context in which it appeared, and would perhaps recognize it in many contexts, I cannot say I would be able to recall it while writing. Notice the irony of the word’s double meaning.

From Oxford American Dictionaries:

1. An even toed ungulate mammal that chews the cud regurgitated from its rumen. The ruminants comprise the cattle, sheep, antelope, deer, giraffes, and their relatives.
2. A contemplative person; a person given to meditation.

From George Orwell’s 1984:

The war, therefore, if we judge it by the standards of previous wars, is merely an imposture. It is like the battles between certain ruminant animals whose horns are set at such an angle that they are incapable of hurting one another. But though it is unreal it is not meaningless.