Economical is the usual form when meaning frugal, saving; economic is the form commonly used when meaning pertaining to the management of a household, or of public affairs.
E`co*nom"ic*al*ly (?), adv. With economy; with careful management; with prudence in expenditure.
E`co*nom"ics (`k&ocr*;nm"ks), n. [Gr. ta` o'ikonomika`, equiv. to "h o'ikonomi`a. See Economic.] 1. The science of household affairs, or of domestic management.
2. Political economy; the science of the utilities or the useful application of wealth or material resources. See Political economy, under Political. "In politics and economics." V. Knox.
E*con"o*mist (?), n. [Cf. F. économiste.] 1. One who economizes, or manages domestic or other concerns with frugality; one who expends money, time, or labor, judiciously, and without waste. "Economists even to parsimony." Burke.