Somanassa: lit 'glad-minded-ness' su+manas+ya gladness, joy; identical with 'mentally pleasant feeling' cetasikā, sukhā belongs to the feeling-group vedanā -khandha see: khandha, and is enumerated amongst the 22 abilities indriya. It may or may not be associated with kammically advantageous consciousness with kammically disadvantageous consciousness greedy c. ib. 22-25, and with kammically neutral consciousness ib. 40, 42-45, 57-60, 66-69, 72-76. 81-84, - somanassa is not identical with pīti.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.