"proud, arrogant," 1918, noted that year as college slang, from snoot (n.) + -y (2). Probably with suggestions of snouty (1858); the notion being of "looking down one's nose." Related: Snootily; snootiness.
Snobbish; haughty and disdainful; supercilious; hoity-toity, sniffy: the snootiest madame in America/ a generally vain and snooty class of men
[1919+; fr the mien of a person who smells something nasty and holds the nose high]