Yes, RECESSION is a Scrabble word!

Letter values in Scrabble US: R 1, E 1, C 3, E 1, S 1, S 1, I 1, O 1, N 1.

Is it a valid word?

RECESSION is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the state of the economy declines; a widespread decline in the GDP and employment and trade lasting from six months to a year
a small concavity
the withdrawal of the clergy and choir from the chancel to the vestry at the end of a church service
the act of ceding back
the act of becoming more distant

Also: ceding back.