N'ime kemịkalụ, esters bụ kemịkalụ ndị a na-enweta site na mkpokọta nke acid na mmanya.
N'ezie, nsụgharị dị mgbagwoju anya nke ahịrịokwu ahụ bụ "Na kemịkalụ, esters bụ ihe ndị na-emepụta kemịkalụ nke sitere na inorganic acid ma ọ bụ organic acid nke ọ dịkarịa ala otu - OH (hydroxyl) otu nọchiri anya otu - O - alkyl (alkoxy) otu. "