Lonely

google

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late 16th century: from lone + -ly1.

wiktionary

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From lone +‎ -ly, or from an apheretic shortening of alonely. See lone.

etymonline

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lonely (adj.)

c. 1600, "solitary, lone; unfrequented," from lone + -ly (1). Meaning "dejected for want of company" is from 1811. Lonely heart (n.) "a lonely-hearted person" is from 1922. Lonely hearted (adj.) is attested from 1820.