We couldn't find a direct definition for the term sp. gr.
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Sap-sucker, sapsucker, saskabusher, savagery, schwabacher, sea poacher, sea poker, see figure 1, sheep shearer, sheep-shearer, sheepshagger, shopgoer, six-figure, skip car, soapbox car, sp. gr., spabooker, spacer, spacewar, spacewar!, spacewear, spacker, spagoer, spaser, spazzer