As a synonym of "by the way", use commas to set off the conjunctive adverb "incidentally". When modifying a single word (typically to remark on a coincidence), do not use commas to separate "incidentally" from the word (verb, adjective, or adverb) it describes.

As a synonym of "by the way", use commas to set off the conjunctive adverb "incidentally".

Mediterranean food is delicious. Incidentally, it also has incredible health benefits.

Mediterranean food is delicious. Incidentally it also has incredible health benefits.

When modifying a single word (typically to remark on a coincidence), do not use commas to separate "incidentally" from the word (verb, adjective, or adverb) it describes.

The disease was diagnosed incidentally by routine analysis.

1. Meanings of 'Incidentally'

"Incidentally" has two basic meanings:

• "By the way" (e.g., "I'd like to learn Chinese. Incidentally, China's language supersedes others in complexity.")
• "By chance" (e.g., "They fish for cod but catch other species incidentally.")

2. 'Incidentally' as a Synonym of 'By the way'

We can use "incidentally" as a more formal way to say "by the way".

He was a great teacher. Incidentally, he taught me everything I know about general relativity and electromagnetism.

"Incidentally" helps us introduce a further remark or comment not completely connected to the current subject.

Vegetables will help you control your weight. Incidentally, they are important sources of vitamins and minerals.

In sentences like these, "incidentally" is a sentence adverb and should be followed by a comma at the start of a sentence.

India's rising inflation is putting pressure on the government. Incidentally, the next Indian general election is speculated to be held in April.

Conjunctive adverbs can also be placed in the middle of a sentence or clause. In this case, enclose "incidentally" in commas to signal that the adverb modifies a whole clause or sentence.

It seems that life gets more and more expensive every year. I am facing, incidentally, a significant rent increase.

In mid-sentence, remember to add both commas. The closing comma (appositive comma) is also important and should not be omitted.

Sales are not improving. Rebecca, incidentally, thinks that financial conditions are being affected.

Sales are not improving. Rebecca, incidentally thinks that financial conditions are being affected.

But we often place "incidentally" at the start of a sentence to signal the transition into a new subject.

The most populous countries in the world are China, India, and the US. Incidentally, the United States' economy is the largest as measured by nominal GDP.

3. 'Incidentally' as a Synonym of 'By chance'

"Incidentally" can also be used to remark on a coincidence, that is, to express that something happens "by chance" or "not intentionally".

The subject was incidentally mentioned in an article about healthy habits for kids.

In this case, "incidentally" modifies a single word (verb, adjective, or adverb).

She might have incidentally benefited from these activities.

We do not generally use commas to separate regular adverbs from the word they describe.

Her remarks were incidentally hilarious.

But use a comma before or after "incidentally" when required by a particular sentence structure. For example, commas may be necessary to enclose nonessential information or parenthetic expressions.

This is a serious condition, often diagnosed incidentally, that should be treated as soon as possible.