1 : a state or condition in which something expected, wanted, or looked for is not present or does not exist : a state or condition in which something is absent an absence [=lack] of detail In the absence of reform [=without reform], progress will be slow.

vertical, perpendicular, plumb mean being at right angles to a base line. vertical suggests a line or direction rising straight upward toward a zenith. the side of the cliff is almost vertical perpendicular may stress the straightness of a line making a right angle with any other line, not necessarily a horizontal one.

Opposite of a lack or deficiency of something. presence. existence. incidence. appearance.

Absent is a word in English language that is used to refer to something or someone who is not present or missing. Absence is another word that is the state of being absent. This means that if someone is not present, he is absent and his absence is noted.

noun. state of being away or not being present: I acted as supervisor in his absence. Your absence was noted on the records.

Absence usually signifies that something is not there. Lack of usually means a shortage.

The right answer is that it´s spelled absence, not absense (nor absance).

These words refer to the fact of something not being present or not existing. The most common word is absence. The absence of proof made a conviction impossible. The opposite of absence is presence.

One occurs in the presence of oxygen (aerobic), and one occurs in the absence of oxygen (anaerobic). Both begin with glycolysis – the splitting of glucose. Cellular respiration that proceeds without oxygen is called anaerobic respiration.

If blood oxygen levels are too low, your body may not work properly. Blood carries oxygen to the cells throughout your body to keep them healthy. Hypoxemia can cause mild problems such as headaches and shortness of breath. In severe cases, it can interfere with heart and brain function.