Frequency: The word is one of the 1500 most common words in English.
1.
~ is used as an abbreviation for company when it is part of the name of an organization. (BUSINESS)
...the Blue Star Amusement ~
2.
~ is used as a written abbreviation for county before the names of some counties, especially in Ireland.
...~ Waterford.
3.
You use and co. after someone’s name to mean the group of people associated with that person. (INFORMAL)
Wayne Hussey and co. will be playing two live sets each evening.
PHRASE: n-proper PHR