From lonely + -ness.

• (America) IPA: /ˈloʊnlinəs/

loneliness

1. A feeling of depression resulting from being alone or from having no companions.
   • 1948, Alan Paton, chapter 21, in Cry, the Beloved Country‎, New York: Scribner, page 154:

     We […] feel deep pity for a man who is condemned to the loneliness of being remarkable […]

   • 1997, Bob Dylan, “Marchin’ to the City”, in The Bootleg Series Vol. 8: Tell Tale Signs: Rare and Unreleased 1989–2006‎:

     Loneliness got a mind of its own
     The more people around, the more you feel alone

2. The condition or state of being alone or having no companions.
   • 1645, John Milton, Tetrachordon‎, page 7:

     Hitherto all things that have bin nam’d, were approv’d of God to be very good: lonelines is the first thing which Gods eye nam’d not good […]

   • 1657, Richard Ligon, A True & Exact History of the Island of Barbados, London: Humphrey Moseley, Dedicatory letter to the Bishop of Salisbury,

     [I] was designing a piece of Landscape […] wherein I meant to expresse […] the beauties of the Vegetables, that do adorn that place, in the highest perfection I could: But presently after, being cast into Prison, I was deprived both of light and lonelinesse, two main helpers in that Art […]

   • 1837 February, Boz [pseudonym; Charles Dickens], “Treats of Oliver Twist’s Growth, Education, and Board”, in Oliver Twist; or, The Parish Boy's Progress. […], volume I, London: Richard Bentley, […], published 1838, →OCLC ↗, page 20 ↗:

     Wretched as were the little companions in misery he was leaving behind, they were the only friends he had ever known; and a sense of his loneliness in the great wide world sank into the child’s heart for the first time.

3. The state of being unfrequented or devoid of human activity (of a place or time).
   • 1794, Ann Radcliffe, The Mysteries of Udolpho, London: G.G. & J. Robinson, Volume 4, Chapter 3, p. 50,

     […] as she sat at her bed-side, indulging melancholy reveries, which the loneliness of the hour assisted […]

4. (obsolete) A desire to be alone; disposition to solitude.
   • c. 1604–1605 (date written), William Shakespeare, “All's Well, that Ends Well”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC ↗, [Act I, scene iii]:

     […] I see
     The mystery of your loneliness, and find
     Your salt tears’ head: now to all sense ’tis gross
     You love my son […]

• (depression resulting from being alone) lonesomeness
• (condition of being alone) aloneness, friendlessness, seclusion, solitariness, solitude

• French: solitude
• German: Einsamkeit
• Italian: solitudine
• Portuguese: solidão
• Russian: одино́чество
• Spanish: soledad