Tayammum in the language means to intend.
According to Islamic terminology it is the use of pure dirt as a replacement for water on specific joints for major or minor impurity.
(i) Use of pure dirt: Meaning that one cannot make Tayammum with faeces or urine.
(ii) As a replacement for water (And this occurs in two instances)
(1) When water that purifies is not present.
(2) When one is unable to use water due to
sickness, fear and the like.
Description of Tayammum: One places his hands on the dirt and then blows some of the dirt off from his hands. Then wipes his face and his hands up to his wrists.