The eastern region of Númenor (UT/165), a combination of the prefix orro- of orró- “east” and the plural of the suffix -sta “land”.
Quenya
orro
ugh, alas! ow!
orro
interjection. alas!
orrostar
place name. Eastlands
Orrostar
eastlands
Orrostar place-name, the "Eastlands" of Númenor (UT:165)
orró-
uprising, sunrise, east
orró-, hró- "uprising, sunrise, east" (PE17:18), element underlying words like the following, and also hróna (q.v.)
orró-
prefix. uprising, sunrise, east
orróna
eastern
orróna adj. "eastern" (PE17:18)
orróna
adjective. eastern
horro
ugh, alas! ow!
horro (also orro) interjection "ugh, alas! ow!" (said to be an interjection "of horror, pain, disgust") (VT45:17)
ro-
prefix. uprising, sunrise, east
Ambarónë
uprising, sunrise, orient
Ambarónë noun "uprising, sunrise, Orient" (AM2)
hró-
prefix. east
hróme(n)
noun. east
hróna
eastern
hróna adj. "eastern" (PE17:18), apparently a variant of róna, q.v. (itself not clearly glossed).
róme
noun. east
rómenya
eastern
rómenya adj. "eastern" (RŌ)
róna
adjective. east
orro (also horro) "ugh, alas! ow!" (interjection "of horror, pain, disgust") (VT45:17)