c.1250,
uglike "frightful or horrible in appearance," from O.N.
uggligr "dreadful, fearful," from
uggr "fear, apprehension, dread" (perhaps related to
agg "strife, hate") +
-ligr "-like." Meaning softened to "very unpleasant to look at" c.1375. Extended sense of "morally offensive" is attested from c.1300; that of "ill-tempered" is from 1687. Among words for this concept,
ugly is unusual in being formed from a root for "fear, dread." More common is a compound meaning "ill-shaped" (e.g. Gk.
dyseides, L.
deformis, Ir.
dochrud, Skt.
ku-rupa). Another Gmc. group has a root sense of "hate, sorrow" (see
loath). Verb
uglify is attested from 1576.
Ugly duckling (1877) is from the story by Hans Christian Andersen, first translated from Danish to English 1846.
Ugly American "U.S. citizen who behaves offensively abroad" is first recorded 1958 as a book title.