armchair

Short definition from Wiktionary

Noun

1. 1
   A chair with supports for the arms or elbows.
2. 2
   A position removed from that which one is

Adjective

1. 1
   Remote from actual involvement, including a person retired from previously active involvement.
2. 2
   Unqualified or uninformed but yet giving advice, especially on technical issues, such as law, architecture, medicine, military theory, or sports; relating to such advice.

Verb

1. 1
   To create based on theory or general knowledge rather than data.
2. 2
   To theorize based on analysis of data that was gathered previously; to reflect.