Chemical elements which are involved in the construction of living tissue and which are needed by both plant and animal. The most important in terms of bulk are carbon, hydrogen and oxygen, with other essential ones including nitrogen, potassium, calcium, sulphur and phosphorus.
a source of nourishment
the financial means whereby one lives; "each child was expected to pay for their keep"; "he applied to the state for support"; "he could no longer earn his own livelihood"
the act of sustaining
the act of sustaining life by food or providing a means of subsistence; "they were in want of sustenance"; "fishing was their main sustainment"
a source of materials to nourish the body
the act of sustaining life by food or providing a means of subsistence
