The plural noun is orchids and the singular noun is orchid; the adjective is also spelled orchid. Example use as an adjective:
The orchid drapes are a great color for this room.
Note: This is a common adjective. A proper adjective is an adjective derived from a proper noun, such as Danish describing something of or from Denmark, or Victorian describing something of or from the time of Queen Victoria. Proper adjectives are always capitalized.
The proper adjective for southwest is "southwestern."
The proper adjective is Haitian.
The proper adjective for Portuguese is "Portuguese."
Vietnamese is the proper adjective for Vietnam.
The proper adjective for George is Georgian.
The proper adjective for Siam is Siamese.
Mayan is itself a proper adjective.
Freudian is the proper adjective for Freud.
The proper adjective for Georgia is Georgian.
No, old is not a proper adjective. A proper adjective is an adjective derived from a proper noun, such as Swiss cheese, Bolivian pottery, Chinese silk, etc.
The proper adjective for Antigua is Antiganantigan
Kuwaiti is the proper adjective for Kuwait.