Water has a density of 1000 kg/m3 by standard definition at its temperature of maximum density 3.98 Â°C and at 0% salinity. Scientists and engineers use water as a baseline for comparing the relative density of various materials. Water with a density of 1000 kg/m3 at 3.98 Â°C has a mass of 1000kg and a volume of 1 m3.
Spelt is a word. It is the past participle of spell. It is also a type of wheat, and therefore also a noun. It depends upon whether you are using British English (and Spelt is correct) or you are using American English.
A homophone is a word that is pronounced the same as another word but differs in meaning, and may differ in spelling. The words may be spelled the same, such as rose (flower) and rose (past tense of rise), or differently, such as carat, caret, and carrot, or to, two, and too. Homophones that are spelled the same are also both homographs and homonyms.