Mammoth Uncensored Word List:
47 - 4 letter words starting with so

soak soap soar sobs sock soda sods sofa soft sogs sohs soil soke sold sole soli solo some soms somy song sons soom soon soop soot soph sops sord sore sorn sort soss soth sots soul soum soup sour sovs sowl sowm sown sowp sows soya soys