Sunnily is from sunny (from Old English sunne 'sun' + -y) plus the adverbial suffix -ly, an English formation. Important recorded forms include sunne (Old English). Morphologically, the -ly ending turns the base adjective or participial form into an adverbial manner word, or preserves an older adjectival pattern where the part of speech allows it. The modern sense is largely compositional, with the historical elements narrowing into a stable English lexical item. In current use it covers in a cheerful, bright, or sunny manner. The wider family includes related words such as sun, sunny, and sunniness.