organiseorganize
Organise
Organize
organife
Organike

Or, any other string that starts a line, begins with a 

letter o in lower or capital case, proceeds 

with rgani, has any character in the 7th position, and ends with the 

letter e.

organise

Organize
organifer
Organi2ed111

Or, any other string that starts a line, begins with a letter o in lower or capital case, proceeds with rgani, has any character in the 7th position, follows with letter e and zero or more characters from the range [A-Za-z0-9].

[Oo]rgani.e\w+$

organiser
Organized
organifer
Organi2ed111

Or, any other string that ends a line, begins with a letter o in lower or capital case, proceeds with rgani, has any character in the 7th position, follows with letter e and one or more characters from the range [A-Za-z0-9].

organise
Organized
organifer
Organi2ek

Or, any other string that starts a line, begins with a letter o in lower or capital case, proceeds with rgani, has any character in the 7th position, follows with letter e, and ends with zero or one characters from the range [A-Za-z0-9].

organise

Organized

organifer
Organi2ek

Or, any other string that starts and ends a line, begins with a letter o in lower or capital case, proceeds with rgani, has any character in the 7th position, follows with letter e and zero or one characters from the range [A-Za-z0-9].

organisers

Organizers
organifers
Organi2ek1

Or, any other string that begins with a letter o in lower or capital case after a word boundary, proceeds with rgani, has any character in the 7th position, follows with letter e, and ends with two characters from the range [A-Za-z0-9].

organise

Organi1e
Organizer
organifed

Or, any other string that begins with a letter o in lower or capital case after a word boundary, proceeds with rgani, has any character in the 7th position, and end with letter e, or any other string that begins with a letter o in lower or capital case after a word boundary, proceeds with rgani, has any character in the 7th position, follows with letter e, and ends with a single character from the range [A-Za-z0-9].

French 

France 

Frence 

Franch

This will also find words where there are characters either side of the solutions above, such as Francer, foobarFrench, and Franch911.

French 

France 

Frence 

Franch

This will also find strings at the end of a line. It will find words where there were characters before these, for example foobarFrench.

^France|^French

This will also find words where there were characters after French such as Frenchness.

\b[Cc]olou?r\b|\bCOLOU?R\b

 /colou?r/i

 
In real life, you should only come across the case insensitive variations colour, color, Colour, Color, COLOUR, and COLOR (rather than, say, coLour). So based on what we know, the logical regular expression is \b[Cc]olou?r\b|\bCOLOU?R\b. An alternative more elegant option we've not discussed is to take advantage of the / delimiters and add an ignore case flag: so /colou?r/i will match all case insensitive variants of colour and color.

\bhead ?rest\b

 
Note that although \bhead\s?rest\b does work, it will also match zero or one tabs or newline characters between head and rest. So again, although in most real world cases it will be fine, it isn't strictly correct.

\d{4}

 
Note this will also match 4 digit strings within longer strings of numbers and letters.

\b\d{2}-\d{2}-\d{4}\b

 
Depending on your data, you may chose to remove the word bounding.

\d{2}-\d{2}-\d{2,4}$

 
Note this will also find strings such as 31-01-198 at the end of a line, so you may wish to check your data and revise the expression to exclude false positives. Depending on your data, you may chose to add word bounding at the start of the expression.

.* : .*, \d{4}

 
Without word boundaries you will find that this matches any text you put before British or Manchester. Nevertheless, the regular expression does a good job on the first look up and may be need to be refined on a second depending on your data.