The Grand avenue base ball grounds will be the scene of an exciting encounter this afternoon between the St. Louis Brown Stockings and a very strong semi-professional team from Cincinnati. The latter will reach the city in the morning, and will remain over until Sunday evening, playing the Browns to-day and tomorrow…So as to give gentlemen detained in town by business ample time to attend the game, it will not be called until 4 o’clock.
St. Louis Globe-Democrat, May 28, 1881
Semi-professional, according to the Oxford Dictionary, means "receiving payment for an activity but not relying entirely upon it for a living." The use of the term goes back to at least 1843, according to the Online Etymology Dictionary, and possibly as far back as 1824. But the term has a more specific meaning when applied to sports and, at least in its modern usage, is used disparagingly in an attempt to distinguish between the "true" professionals and those who play the game at a lower level.
The guys who played for the Brown Stockings and Cincinnati were as much professional baseball players as were the guys playing for Worcester or Troy in the National League in 1881. You think the guys for Worcester didn't have jobs in the off-season? By definition, pretty much every baseball player in the National League was a semi-professional, as were the guys on the Brown Stockings. In that sense, semi-professional is an accurate description.
But that's not how the term is being used here or in contemporary descriptions of these clubs. What they're really trying to say is that they're a minor club. They're trying to distinguish between the "big" clubs that played "major" league baseball and the professional clubs that didn't. Ned Cuthbert, the Gleason brothers, Trick McSorely, Pidge Morgan, and the rest of the guys on the Brown Stockings were not amateur baseball players and they hadn't been for a long time. They got paid to pay baseball just the same as Cap Anson. The guys on Cincinnati got paid to play baseball. They were professional baseball players. The Brown Stockings and Cincinnati were trying to get the best players and put together the best team they could. And they were paying money to do so. They were professional baseball clubs.
The phrase that I've come up with to describe the Interregnum Brown Stockings is "minor, independent, professional baseball club." I think that's a very accurate description of what they were and is substantially more accurate than "semi-professional." They were a minor club. They weren't playing the big boys. They weren't in the "major" league. They weren't competing for the national championship. They actually weren't playing in any league and were, like some college football teams used to be, an independent. But the team existed to make money and they were certainly paying their players. So it was absolutely a professional club and stocked with professional players.
So whenever you see the Interregnum Brown Stockings described as semi-professional, just keep in mind that the writer is using that as a bit of short-hand because he's either too lazy to write what he really means or doesn't understand the true nature of the club. We can forgive a writer in 1881 for using the phrase because they were still in the process of developing a language to describe baseball. The game was evolving and the language used to describe it had to evolve as well. Eventually, we would develop the idea of major and minor league clubs but, in 1881, we weren't really there yet. But there is no excuse, in 2014, to use the term semi-professional to describe a club like the 1881 Brown Stockings. It's just inaccurate and poor historical writing.