Ill or Sick?

What Is the Difference between "Ill" and "Sick"?

"Ill" and "sick" are easy to confuse because they both describe poor health. However, there is a difference between "ill" and "sick."

The adjectives "ill" and "sick" both mean "unwell." With the exception of their use in set terms (e.g., sick leave, ill health), "ill" and "sick" can usually be used interchangeably, but "sick" dominates in both the UK and the US.

In British English, "ill" is used a little more commonly than in the US (especially with the verb "to feel").

In both American and British English, "sick" is the preferred word when someone is physically vomiting or feeling unwell temporarily.

The following graph shows how "sick" dominates over "ill" in UK and the US:

More about "Ill" and "Sick"

"Sick" is commonly seem in these terms:

• sick day
• sick leave
• sick pay
• seasick
• carsick
• sick and tired

"Ill" is commonly seen in these terms:

• terminally ill
• ill-health
• to take ill

Example Sentences with "Sick" and "Ill"

Here are some examples featuring "sick" and "ill":

• I can't travel by boat because I feel sick immediately.
(Here, "sick" refers to physically vomiting. In this context, "sick" is preferred over "ill.")
• Being healthy is the crown that only the sick can see. A lot of times, we take it for granted. (Comedian Hasan Minhaj)
(Here, "sick" refers to being in poor health. Even in this context, "sick" is more common than "ill.")
• Kate has taken ill with a chest infection.
("To take ill" is a set phrase.)
• The most important thing when ill is to never lose heart. (Premier of the Soviet Union Vladimir Lenin)
(This was a translation by a British interpreter. An American interpreter would likely have used "sick," but both words are an option.)