a roll of hair brushed back from the forehead
"The barber styled his new haircut into a perfect roach, sweeping the thick locks straight back from his forehead."
the butt of a marijuana cigarette
"He carefully saved the roach from his blunt to smoke again later."
street names for flunitrazepan
"The dealer slipped him a small baggie containing roach, which was actually flunitrazepam hidden in plain sight."
European freshwater food fish having a greenish back
"The angler caught a roach from the pond, enjoying its mild flavor and distinctive greenish back."
Certain members of the fish family Cyprinidae, including:
"The geologist carefully mapped each roach of coal within the ancient sedimentary basin."
Species in the genus Rutilus, especially
A cockroach.
An extra curve of material added to the leech (aft edge) of a sail to increase the sail area.
Marijuana; cannabis used as a drug.
A bed or stratum of some mineral.
In plain English: A roach is a small, flat insect that often lives near drains and sinks.
"The roach scurried across the kitchen floor after someone dropped food on the ground."
Usage: In sailing contexts, a roach refers specifically to an extra curve added to the aft edge of a sail to expand its surface area. Avoid confusing this technical term with common insects or fish unless discussing those specific subjects directly.
A surname.
"Roach is a famous American actor whose full name is William Roach."
The word roach comes from Old French and Middle Low German, where it originally meant "ray," a type of fish. Its ultimate origin is likely the Proto-Germanic word *rūhaz, which described something rough.