As an adjective, ordinary.
As a noun relating to land, a plain is an area of land not significantly higher than adjacent areas and with relatively minor differences in elevation, such as a flood plain along a river or the Great Plains of the Mid-western United States.
"Plain People" refers to Amish, Mennonites, Quakers and other groups of Christians who hold to a simple life-style and do not artificially beautify their clothes or possessions.
It is Hebrew meaning "a fertile plain"
plain
E
Milan may be Gaulish in origin meaning "middle plain".
Plain well-meaning Briton. has written: 'A whipper for levelling Tommy' -- subject(s): Politics and government, Constitutional law
plain
"In plain sight" is referring to something being in front of you without any type of obstructions blocking sight of it.
inconspicuous means that
ομαλός
easy, effortless, light, plain
grassland, plain, prairie, savanna
It is flat. Meaning it is just plain and straight.