Serthan, n. a precipice, a cliff
Serthedd, n. steepness; obscenity
Serthi, n. obscenity
Serthiant, n. steepness
Serthol, a. precipitous; obscene
Serthu, v. to make steep; to grow steep; to grow obscenely
Serthus, a. declivious; obscene
Serw, a. sparkling, glittering
Serydd, n. an astronomer
Seryddiaeth, n. astronomy