I agree with Prof. Mathew Kapstein.
 
The word Siddha has several meanings in several contexts.
 
The term JIvanmukta too has a huge shades of meaning and a wide varieties of discussion.
 
There are very small number of occasions the two terms can turn almost synonymous to each other.
 
Siddha : 1. The one who has achieved one of the ashTa siddhis. 2. One of the (usually seven) devata jatis. 3. A respectable member of the Tamil siddha tradition. 4. A guru of the Shaiva particularly Vira shaiva tradition 5. In the modern theosophical tradition, the one translated into English as a Master. The list goes on.
 
JIvanmukta : I shall continue in my next post.    

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Prof.Nagaraj Paturi
Hyderabad-500044