Vishishtadvaita is substantiated by Nathamuni, Yamuna and Ramanuja, who are considered great acharyas of this school of thought. It is interesting to know that the term Vishishtadvaita does not find its place anywhere in any of the works of the above-noted acharyas, nor in the works of Vedanta Desika, and not even in the works of writers coming after the period of Sudarshanasuri, a well known commentator on Sri Bhashya of Ramanuja. Sudarshanasuri was the first person to refer to the system as Vishishtadvaita and became subsequently used from the 16th century CE.
The term may be derived in two ways, namely, Vishishtasya advaitam and Vishishtayoh advaitam. The term understood in the first derivation is qualified (Vishishta). This comes to mean that there is only reality understood as the Qualified Brahman, since chit (animate beings – sentient) and achit (ianimate beings – insentient) are its modes (prakara) and they are no longer separated from Brahman which is substantive (Vishishta). On this score it does not mean that there is no difference between the modes and Brahman and also among the modes themselves. All that the compound suggests is that Brahman is qualified and that it has no second one. The second derivation indicates the identity between two qualified Brahmans. In reality there is only one Brahman, forming the cause of the universe. The same Brahman becomes the effect also. The cause will be in subtle form, and the effect will be in gross form. It is Vishishta in both cause and effect. No doubt we do not come across this term in the works of Ramanuja; however, he refers to oneness of the qualified as the basis for the system.