diner-n; 3 Senses

Sense Number 1: a person eating a meal, often in a restaurant

Commentary: DINER[+person][+eater] [+role][+eater][+meal]

Examples:
The diner knocked over his wine glass reaching for the salt shaker.
John is a frequent diner at the new Vietnamese restaurant.
Diners will enjoy the beautiful outdoor deck overlooking the sea.
The seagulls were unwelcome diners at our beach picnic. (figurative/ironic)
Two of the diners at Mary's Thanksgiving dinner became ill from the mushroom soup.

Mappings:
WordNet 3.0 Sense Numbers: 1

Sense Number 2: a railcar on a train where food is served and eaten

Commentary: DINER[+vehicle][+car][+train][+eating]

Examples:
We had a glorious lunch in the diner of a first-class Italian train.
Most American trains no longer have real diners but just simple snack cars.
We could only get reservations for the second seating in the diner car.

Mappings:
WordNet 3.0 Sense Numbers: 2

Sense Number 3: a casual restaurant resembling a dining car on a train

Commentary: DINER[+building][+railcar][+restaurant][+casual]

Examples:
Bob ordered a hamburger, fries and a large chocolate shake at the local diner.
The waitresses in that diner wear pink uniforms and short white aprons.
It's a fashionable new downtown diner with 50's retro decor.

Mappings:
WordNet 3.0 Sense Numbers: 3