These words all relate to a lack or loss of friendship, love or interrelateness with others. Loneliness is the least formal and the most restricted in its application. It refers to a lack of companionship and usually implies an attendant feeling of unhappiness or unfulfilment: the stark loneliness of the widows and pensioners who live in residentials. The word may refer to a feeling rather than an actual condition of isolation: Her loneliness was never more acute than in a crowded theatre. Occasionally, the word can refer to a welcome state of seclusion or solitude: enjoying the loneliness of their life on the island. Also, the word can refer to the physical isolation of anything, whether this is regarded as pleasant, unpleasant or factually neutral the loneliness of a single tree silhouetted against the sky; the loneliness of their hut high in the mountains.

One use of desolation can serve as an intensification of loneliness in referring to someone utterly alone or inconsolably forsaken: the desolation of the city’s derelicts. Often the word can indicate an actual state of ruin or barrenness: the desolation left behind by the cyclone; the desolation of the Australian outback. The word can also refer to intense sorrow suffered because of a serious loss: the desolation he felt upon hearing the news of his brother’s death.

Disaffection is relatively formal; unlike the former pair, it most often suggests that an earlier fondness for someone has turned to indifference or mild distaste: She had regarded her husband over the years with a growing disaffection . Neither a complete separation from someone nor a transmutation of fondness into hatred need be suggested by the word. Often it has a stronger charge when it indicates someone deliberately at work to cause a more drastic change in feeling or allegiance, as in intrigues of love or politics: an envious friend who had actively promoted disaffection between the newly married couple; professional agitators who worked zealously to stir up disaffection and rebellion among the workers. Estrangement applies more exclusively to a voluntary disaffection that results in complete separation and, sometimes, a stronger feeling of dislike or hatred that replaces an earlier fondness or love: It was impossible to keep their estrangement secret, since they were living apart and had drawn up separation papers. Sometimes the word puts its emphasis on a process of cooling affection, without suggesting any compete break; here, it is close to disaffection , but it suggests a growing remoteness and lack of communication that may be involuntary: so busy with their separate concerns that neither noticed the estrangement that was gradually being driven between them like a wedge.

Alienation applies more widely than any other of these words. It can be used in a way resembling the last sense of estrangement , but with a clearer implication that no separation need take place: pressure that resulted in a feeling of alienation towards each other. The phrase, alienation of affection , implies, like disaffection , a deliberate attempt to bring about a reversal of feelings towards someone, but this use of the word is now less common. At its most general, the word can apply to any feeling of unrelatedness, especially a hopeless feeling of distance from society’s structure and concerns: minority groups that must also cope with their own feelings of alienation from a society that rejects them. This fad use of the word derives ultimately from Marxism in which it is a technical term for the separation of a labourer from the fruits of his labour: Unlike the craftsman who took pride in his work, the assembly-line worker feels isolated and indifferent because of the alienation inherent in mass production.