lonely: [16] Lonely is a derivative of lone [14], itself a truncated form of alone. Another coinage based on lone is lonesome [17]. [lonely etymology, lonely origin, 英语词源]
c. 1600, "solitary, lone," 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.