The plural form of matinée is simply matinées.
Matinees is the plural form.
matinee
A Wagner Matinee was created in 1904.
Matinee at the Bijou was created in 1980.
Toy Matinee was created in 1990.
Matinee Idyll was created in 1976.
Matinee Mouse was created in 1966.
The duration of The Matinee Idol is 1.1 hours.
The duration of Matinee Theater is 2880.0 seconds.
The duration of Mumbai Matinee is 2.08 hours.
Today, Ann and I went to see a matinee of Macbeth. There are more matinee showings at the theater during the summer months.
If you mean 3:30 PM, yes it is a matinee.