Definitions
1.AdjectiveStationed in an exposed or hazardous position; hidden in ambush. Originally as sentinel perdu. .mw-parser-output .defdate{font-size:smaller}
2.AdjectiveIn a dangerous situation; lost, desperate.
3.AdjectiveHidden; concealed from sight. Chiefly with lie.
4.NounOne placed on watch, or in ambush.
5.NounA soldier sent on a forlorn hope.