A tactician is a person who is good at planning the small, concrete moves that win a fight, a game, or an argument. The word is close to 'strategist', and people often mix them, but there is a real difference worth keeping. A strategist decides the big aim — which war to fight, which market to enter. A tactician decides the moves on the day — where to put the players, when to attack, which question to ask first. So a tactician works inside a shorter time and a smaller space. You will meet the word most in three places: the military (a general who is a fine tactician), sport (football and basketball writers love it, especially about coaches), and chess and other games. It also gets used about politicians, and there it is a little bit two-sided: calling a politician 'a brilliant tactician' can quietly mean 'clever at winning today, but with no big plan'. The word is fairly formal — you read it in newspapers and books more than you hear it in a café. It is almost always used with a good word in front, like 'a shrewd tactician', 'a master tactician', 'a fine tactician'. There is no common negative version; if someone is bad at this, people just say they are a poor tactician, and that sounds a bit odd, so they usually say something else instead.