What is another word for "main"?

Roget's Thesaurus (1911) lists these synonyms for "main": advantage, afloat, all, aright, behalf, behoof, beneficial, benefit, best, blessing, boon, boot, brine, chance, commendable, common, consummation, cotidal, deep, devoutly, dolphin, far, favor, for, fortune, gain, gift, giving, godsend, good, goodness, great, happiness, harvest, high, hydrographer, hydrographic, hydrography, improvement, interest.