I would say that the model you are looking at has a solid wood soundboard, but laminate sides and back. When Washburn makes an all solid-wood guitar, they are quite specific about it when they determine the model designation.
52=Washburn model number
S=solid wood soundboard (if it were an all solid-wood guitar, it would read SW rather than just S after the model number, therefore an all solid wood D52 would carry a model designation of D52SW).
Hope that helps.
YerDugliness, Esq./Post No Bills
Guitar Playin' FOOL, retired & attempting to age disgracefully!!
Washburns: WD32SW, D61SW, and C124SW
Other fine acoustic guitars by Breedlove (custom shop Revival Series 000), Darren Hippner (#506), Takamini (2005 LTD), Epiphone (Masterbilt AJ500RC), and Yamaha (G231-II)