Webster's Revised Unabridged Dictionary · 1913

Sugar

Sugar , noun

[Old English sugre, French sucre (compare Italian zucchero, Sp. azúcar), from Arabic sukkar, assukkar, from Sanskrit carkarā sugar, gravel; compare Per. shakar. Compare Saccharine, Sucrose.]

1.
A sweet white (or brownish yellow) crystalline substance, of a sandy or granular consistency, obtained by crystallizing the evaporated juice of certain plants, as the sugar cane, sorghum, beet root, sugar maple, etc. It is used for seasoning and preserving many kinds of food and drink. Ordinary sugar is essentially sucrose. See the Note below.

The term sugar includes several commercial grades, as the white or refined, granulated, loaf or lump, and the raw brown or muscovado. In a more general sense, it includes several distinct chemical compounds, as the glucoses, or grape sugars (including glucose proper, dextrose, and levulose), and the sucroses, or true sugars (as cane sugar). All sugars are carbohydrates. See Carbohydrate. The glucoses, or grape sugars, are ketone alcohols of the formula C6H12O6, and they turn the plane of polarization to the right or the left. They are produced from the amyloses and sucroses, as by the action of heat and acids of ferments, and are themselves decomposed by fermentation into alcohol and carbon dioxide. The only sugar (called acrose) as yet produced artificially belongs to this class. The sucroses, or cane sugars, are doubled glucose anhydrides of the formula C12H22O11. They are usually not fermentable as such (compare Sucrose), and they act on polarized light.

2.
By extension, anything resembling sugar in taste or appearance; as, sugar of lead (lead acetate), a poisonous white crystalline substance having a sweet taste.
3.
Compliment or flattery used to disguise or render acceptable something obnoxious; honeyed or soothing words. [Colloquial]
Why, do not or know you, grannam, and that sugar loaf? — J. Webster

Sugar , intransitive verb

In making maple sugar, to complete the process of boiling down the sirup till it is thick enough to crystallize; to approach or reach the state of granulation; -- with the preposition off. [Local, United States]

Sugar , transitive verb

1.
To impregnate, season, cover, or sprinkle with sugar; to mix sugar with.
When I sugar my liquor. — G. Eliot
2.
To cover with soft words; to disguise by flattery; to compliment; to sweeten; as, to sugar reproof.
With devotion's visage And pious action we do sugar o'er The devil himself. — Shakespeare