A suit was an item of clothing. Suits including trousers were known as trouser suits while those with skirts were known as skirt suits.
The Doctor's suits
The Tenth Doctor used to wear two main suits, a dark brown suit with blue pinstripes, (TV: The Christmas Invasion onwards) and a blue suit with red pinstripes. (TV: Smith and Jones onwards) For certain formal occasions, he would also don a tuxedo. (TV: Rise of the Cybermen, The Lazarus Experiment, Voyage of the Damned)
History
While on Earth, members of the Council of Dead wore identical pin-stripe suits and bowler hats to cover their horns. (PROSE: Snowfall, Attack of the Snowmen)
Bill B Brooks, an agent of Jason Dungeon, wore a suit with a flashy red and yellow tie when he met the Tenth Doctor. (PROSE: The Pictures of Emptiness)
Besnik Lucca, the most dangerous criminal in Cardiff in the early 21st century, always dressed in a crisp linen shirt and an Armani suit. (PROSE: SkyPoint)
In September 2005, journalist Cathy Salt wore a brown trouser suit. (TV: Boom Town)
In 2007, the Abzorbaloff, disguised as the human "Victor Kennedy", wore a black suit. In his true form, however, he wore nothing but underpants. (TV: Love & Monsters)
On the day of the Battle of Canary Wharf in 2007, Yvonne Hartman, director of Torchwood One, wore a black skirt suit. Adeola Oshodi wore a brown skirt suit. (TV: Army of Ghosts/Doomsday)
One BBC newsreader who served in the late 2000s and early 2010s was recurringly seen in a grey suit. (TV: Invasion of the Bane, The Sound of Drums, The Bells of Saint John)
In 2008, while working as PR agent for Lazarus Laboratories and 10 Downing Street, Tish Jones wore a black skirt suit. (TV: The Lazarus Experiment, The Sound of Drums)
In 2009, while investigating Adipose Industries, Donna Noble wore a black skirt suit with tights on Tuesday, followed by a black trouser suit on Wednesday. Penny Carter wore a grey trouser suit. (TV: Partners in Crime)
In 2012, Diana Goddard wore a black skirt suit at GeoComTex. (TV: Dalek)
In 2050, June Turner, an inspector of the Department, wore a dark grey skirt suit. (TV: Regeneration-Hound of the Korven)