Apadana is the taking away, removal, ablation, etc., and hence it denotes a thing from which another thing or object is removed. But in Hindu tradition it is popularly known as a technical term of Sanskrit grammar and is used in the sense of the fifth or ablative case.
Technically, apadana or ablation means a noun whose relation
to an action is that of a fixed point, from which departure takes place
(dhruvam apaye apadanam – Panini – Atadhyaye I.4.24). In Sanskrit, apadana or
ablative case is understood from the use of the same with the fifth case-affix,
e.g. gramad Ayati ‘he comes from the village’. In this sentence ‘gramat’, is
ablative and fifth case-affix is employed. Several spheres of action are
treated as apadana in Sanskrit grammar. Some of these are – taking away,
removal, ablation, etc. Hence it denotes a thing from which another thing or
object is separated.
A noun whose relation to an action is that of a fixed point
from which separation takes place is called Apadana or ablation. This can be explained
by the two sutras – apadana Panchami (2-3-28) which means ‘the principal sense
of the Ablative case is apadana or motion away from’ and dhruvam apaye apadanam
(1-4-24) which means ‘from which departure takes place’ as explained by Panini.
In the example ‘gramad ayat’ (comes from a village) ‘parvatadavarohati’
(he descends from the mountain), the Apadana takes the fifth case. When,
therefore, this relation is to be expressed, the fixed point (like grama,
parvata) which is the limit denoted by a word dependent on a verb, is called
ablation.
Moreover words having the sense of jugupsa (conversion), virama
(cessation pause), pramada (swerving from) are used in the ablative case denoting
apadana.