Synonyms for Lonesome (same or very similar meaning)
WordNet sense 1 (being the only one; single and isolated from others):
lone, only, sole, solitary
WordNet sense 2 (existing alone or consisting of one entity or part or aspect or individual):
single
WordNet sense 3 (marked by dejection from being alone):
lonely
WordNet sense 4 (affected or marked by low spirits):
dejected
From the ODE community, based on WordNet
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