Humilitas, Humus: The Earth Which Is Beneath Us

     "The word humility signifies lowliness or submissiveness and it is derived from the Latin humilitas or, as St. Thomas says, from humus, i.e. the earth which is beneath us. As applied to persons and things it means that which is abject, ignoble, or of poor condition, as we ordinarily say, not worth much. Thus we say that a man is of humble birth or that a house is a humble dwelling. As restricted to persons, humility is understood also in the sense of afflictions or miseries, which may be inflicted by external agents, as when a man humiliates another by causing him pain or suffering. It is in this sense that others may bring about humiliations and subject us to them.
     Humility in a higher and ethical sense is that by which a man has a modest estimate of his own worth, and submits himself to others. According to this meaning no man can humiliate another, but only himself, and this he can do properly only when aided by Divine grace. We are treating here of humility in this sense, that is, of the virtue of humility."
- http://www.newadvent.org/cathen/07543b.htm