-ly

from The Century Dictionary.

• An obsolete form of lie .
• A common adjective suffix, forming, from nouns, adjectives signifying ‘of the form or nature of’ or ‘like’ the thing denoted by the noun: as in manly, womanly, godly, lordly, princely, of the nature of, like, or suited to a man, woman, etc.; bodily, earthly, daily, weekly, monthly, yearly, etc., belonging to or being of the body, the earth, a day, etc.; lovely, heartly (obs.), etc.
• A common adverbial suffix, forming from adjectives adverbs signifying ‘in a manner’ denoted by the adjective: as, quickly, slowly, coldly, hotly, etc., loudly, harshly, etc.

from the GNU version of the Collaborative International Dictionary of English.

• suffix A suffix forming adjectives and adverbs, and denoting likeness or resemblance.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• suffix Used to form adjectives from nouns, the adjectives having the sense of "like or characteristic of what is denoted by the noun".
• suffix Used to form adverbs from adjectives.