Semicolon (;)

The semicolon or semi-colon (;) is a punctuation mark that separates major sentence elements. A semicolon can be used between two closely related independent clauses, provided they are not already joined by a coordinating conjunction.

What is a semicolon?

A semicolon, or semi-colon, (;) consists of a period mark placed directly above a comma (resembling the number “9” with the hole filled in). Aldus Manutius the Elder first used a printed semicolon in 1494, and established its use to separate opposed meaning words in order to allow fast direction change in the connection of interdependent statements. Benjamin Jonson, the notable English playwright, poet, actor, and literary critic was the first to use the semicolon systematically in the 17th century. Examples of his work in which semicolons can be found are Every Man in His Humour (1598) and The Alchemist (1610).

Semicolons - Usage rules

The semicolon is used to separate two closely related independent clauses in writing. These clauses must not already be joined by a coordinating conjunction.

Example #1: The train had been late quite a bit in the past month or so; my mother believed it was due to the weather in the Surrey region this time of year.

Semicolons are also used to denote the different items on a list, especially when those items contain commas or a large amount of information.

Example #2: If I’d had my druthers, I would have included snake-bite oil and cough syrup; aloe and sand-flea lotion; and haircutting scissors in my Stranded-on-a-Desert Island Kit this year.

Semicolons are also used to link related clauses.

Example #3: The best way to keep a friendship going through the years is to avoid petty arguments, insisting on one’s own way, and biting remarks about appearance; frequently tell the friend how much he or she is appreciated; and prevent other friendships from interfering.

Relationship to sentence structure

In the English language, period marks, exclamation marks and question marks (also known as terminal marks) mark the end of a sentence, however the semicolon, colon, and comma are sentence internal. Click here to browse various definitions for punctuation marks. This is also known as second boundary punctuation. In this case, the semicolon falls between the terminal marks and the comma; thus its strength is equal to a colon. 

There are several constraints on the use of semicolons in the English language. 

Constraints when using semicolons

The first is when the semicolon marks the left boundary of a constituent, otherwise known as the beginning of a clause or phrase. In this case the boundary is marked by punctuation of greater or equal strength. Also, when two or more semicolons are used within a single construction, all constituents must be at the same level. (This is dissimilar to comma use, wherein commas can separate subordinate and main clauses in one sentence).

Semicolons are always followed by a lower case letter, unless that letter is the beginning of a proper noun (a person, place or thing such as “Tom,” “Alabama,” or “Tiffany lamp”). Semicolons should have no space before them and one space after, coming before the next word. Semicolons should be placed outside ending quotation marks in most cases, although this is a fairly recent convention, according to the Chicago Manual of Style.

In a list, in is important to note that semicolons function as serial commas in series or listings containing internal punctuation – this is their most common use.