The usage of that term is colloquial so “sportcoat”, “sportscoat”, “sport coat”, “sports coat”, “sport jacket”, “sports jacket” are all correct in some sense. If I were you, I’d call up J. Press and ask someone there what term they use :-)
I wonder if this is regional like the soda/pop divide in America or is the utilization choice based on some other cultural demographic of which we are now unaware?
It brings up the question of the relationship of blazer to sport coat. (All blazers are sport coats but not all sport coats are blazers.) It is my understanding that the blazer actually got its name from its participation in the sport of rowing- or maybe just boating. I think the Cambridge Lady Margaret Boat Club rowers were outfitted in “blazing” red coats.
Anyway, based on the usage range posted so far, I suspect there is not a definitive answer unless someone wants to contact Wm. Safire and see if he is willing to venture into the fray!
“Odd jacket.” In the early days of the lounge suit (the modern business suit), men often paired the jacket of their navy blue serge suits with white or gray flannel trousers to wear for casual occasions such as at a resort on vacation or to view spectator sports. Later, separate jackets, made up in fabrics (e.g., bold tweeds and bright colors) and/or with details (e.g., pleated and belted backs, patch and bellows pockets) not acceptable for business wear, began to be worn in such casual settings. The jackets were called “odd” because they did not have matching trousers to make up a suit. Because they were often worn to sporting events, they came to be called “sport” or “sports” coats or jackets. “Odd jacket” covers all permutations; however, I suppose that when I ask any employee under 50 at the typical men’s retail establishment to view the odd jackets, it is I that am viewed as odd. I do it anyway as I rarely wear such jackets to any sporting events, having sold off the polo ponies and the thoroughbreds.
Re: oldog/oldtrix your comment makes me wonder whether the etymology of “sport coat” might not come from the other meaning of “sport” – something surprising and out of the ordinary, odd. Usually you see this meaning of sport in biology/genetics.
I personally say “sports coat”, but I suspect it’s just a regional thing. Americans tend to talk about “sports” as a group of activities, and English people tend to talk about “sport”.
I believe that blazers were named after the jackets worn by the crew on HMS Blazer for a visit by Queen Victoria. Like many other items of naval uniform, they leaked into the mainstream and are now considered very smart and not practical clothing. A sports coat (any variation) is from the shooting-type jacket – tweed with pockets. I got this from some mess dress regulations from the RAF.
Linguistically this is a very interesting discussion! If (and I believe this is so) the original form of the compound is ‘Sportcoat’, then it would be very logical for the form ‘sportscoat’ to appear. The consonant sequence ‘tc’ is not allowed, so the ‘s’ is interjected to make it more salient. And as with all things in Language, as long as both are being used in everyday speech, and everyone knows what you mean, both are acceptable.