We don't have synonyms for sheerwater yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are shearwater, superwater and sweetwater.
(n) :
Alternative spelling of shearwater. [Any of the long-winged pelagic seabirds of the family Procellariidae in genera Puffinus, Ardenna, and Calonectris, that breed on islands and coastal cliffs.]
(n) :
Alternative spelling of shearwater. [Any of the long-winged pelagic seabirds of the family Procellariidae in genera Puffinus, Ardenna, and Calonectris, that breed on islands and coastal cliffs.]