His Only Pants - 1915 was released on:
USA: 2 April 1915
The Only Son - 1915 was released on: USA: 2 April 1915
The Only Way Out - 1915 was released on: USA: 18 March 1915
Only the Maid - 1915 was released on: USA: 22 March 1915
Only a Tramp - 1915 was released on: USA: 19 March 1915
Only a Messenger Boy - 1915 was released on: USA: 23 August 1915
One Performance Only - 1915 was released on: USA: 11 September 1915
Only a Country Girl - 1915 was released on: USA: 30 November 1915
He Was Only a Bathing Suit Salesman - 1915 was released on: USA: 1 December 1915
The cast of His Only Pants - 1915 includes: Lee Moran as The Artist Billie Rhodes as Miss Brownlee
When Is a Cousin - 1915 was released on: USA: 27 February 1915
two legs
There is no singular form it is just pants. Example I only have one pair of pants.