What Does Blood Is Thicker Than Water Mean?

Blood is, in fact, thicker or more viscous than water. But the well-known proverb and idiomatic phrase blood is thicker than water actually has nothing to do with the consistency of either substance. So what does it mean? Keep reading to find out.

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What Does Blood Is Thicker Than Water Mean?

This phrase is used to express the idea that family ties are more important than other social ties, i.e. friendships or romantic relationships; that family bonds, or those connections you have with your family members, are stronger bonds than those formed with the people in your life to which you’re not related. Put another way, blood is thicker than water means that family comes, or at least should come, first. 

The expression can be used in a variety of ways, with different intentions. For instance, it can be said as a reminder or admonishment to someone in a situation that requires they choose between a relative or maybe a best friend. Likewise, it can be used to reprimand someone who, say, shows allegiance to their husband or wife rather than their mother or brother. Of course, it can also be said or written with very positive intentions, simply to express a family’s great dedication to all of its members.

Here are some example sentences using the idiom and proverb blood is thicker than water:

  • When Mary told her mother she was going to spend Christmas with her boyfriend, her mom was disappointed and replied, “Blood is thicker than water.”
  • Tim was tempted to side with his in-laws in their fight with his parents, but he didn’t because blood is thicker than water. 
  • My family can drive me crazy, but I love them and will always be there for them no matter what; after all, blood is thicker than water.

You may also hear or see the phrase written as blood runs thicker than water. The meaning is the same, and the two expressions can be used interchangeably. You could use blood runs thicker than water in place of blood is thicker than water in the example sentences above, and can use it anytime you want to express that family comes first.

The Origins of the Phrase Blood Is Thicker Than Water

As is often the case with so many common phrases we explore at The Word Counter, the origins of this idiom and proverb aren’t certain, and are highly debated.

A first written record of the expression may date to Allan Ramsay’s Collected Scots Proverbs, also known as An Excellent Collection of the Best Scotch Proverbs. Published in 1737, it included the proverb as “Blude’s thicker than water.” (Blude is a Scottish variant of blood.) Documentation may also date earlier, to 1670 and John Ray’s collected Proverbs. It also appeared in the 1789 work Zeluco by Scottish author John Moore: 

“So you see there is little danger of my forgetting them, and far less blood
relations; for surely blood is thicker than water.”

Whatever the date of first documentation, it was certainly in use long before. Some experts guess the phrase dates all the way back to the 12th century and the Middle High German language, specifically to Heinrich der Glîchezære’s epic Reinhart Fuchs, published in 1180. It’s said the English translation of that text is “I also hear it said, kin-blood is not spoiled by water.” Since the translation isn’t an exact match to the phrase as we know it today, it isn’t clear if the proverbs are the same and if the German version is indeed a precursor to the idiom we know and use now.

Likewise, in 1412, the priest John Lydgate expressed a similar sentiment to the expression blood is thicker than water when he wrote, in Troy Book:

“For naturally blood will be of kind
Drawn-to blood, where he may it find.”

If this expression is the origin of the phrase as we know it, it would then be the first recording in the English language.

In 1815, Sir Walter Scott, again using the Scottish variant for the word blood, inserted the phrase in his novel Guy Mannering; or The Astrologer. He writes:

“Weel, blude’s thicker than water; she’s welcome to the cheeses and the hams just the same.”

Perhaps it became popular in the United States beginning in 1859 or 1860, when the U.S. Navy commander Josiah Tattnall, who was delivering an American consul to China, used the phrase to explain why he ultimately came to the aid of the British soldiers engaged in an attack on Taku Forts, thus violating a strict American policy of neutrality. When asked to answer for himself, he simply said, “Blood is thicker than water.” In this case, of course, he wasn’t referring to his relatives, rather a bond or kinship between American and British forces.

Regardless of who first recorded it, and whenever that may have occurred, some believe the expression was born out of the idea that water evaporates without leaving a trace, while blood leaves a stain or some evidence it was there. Thus, it’s more potent or stronger in a way.

Note: You may read that the expression as we use it today originated from the phrase the blood of the covenant is thicker than the water of the womb, with the idea of a blood covenant here being either religious in nature or a pact made between soldiers fighting together in battle. But there’s not much out there to back up this claim.

Understanding Idioms and Proverbs

Blood is thicker than water is both an idiom and a proverb. 

An idiom is an expression with an intended meaning that can’t fully be understood just by looking at the words that comprise it. These words and phrases have a figurative rather than literal meaning. In other words, they don’t mean what they appear to mean. Even if you’ve never heard the term idiom, you have most likely heard many idiomatic expressions. Here are just a few of the most common idioms used today:

You’re in hot water.
His boss gave him the ax.
It’s time to face the music.
You’ve hit the nail on the head.

If you took the first example literally, you’d think it was describing a person standing in a bathtub full of hot water, perhaps. But the expression is actually used to describe a person who’s in trouble. Likewise, rather than literally being handed a tool for chopping wood, if you get the ax from your boss, it means you’re getting fired. It’s time to face the music means that it’s time to come to terms with the consequences of your actions. And when someone has hit the nail on the head, they’ve gotten an answer exactly right or done something exactly as it should have been done.

Even if you knew the rarer definition of thick—to be on close terms with or intimate with; to know well—you’d be hard pressed to understand the figurative meaning of blood is thicker than water just by looking at the words contained within the phrase. As is the case with many, if not most, idioms, you simply need to know the figurative meaning of the phrase outright to understand it.

A proverb is a short, common phrase or expression that imparts wisdom and advice or shares a universal truth. Synonyms of the term proverb include adage and aphorism. Here are some additional examples of well-known proverbs:

Actions speak louder than words.
Absence makes the heart grow fonder.
A picture is worth a thousand words.
Don’t judge a book by its cover.


The proverb and idiomatic expression blood is thicker than water means that family relationships are more important than other relationships, be they those with friends or romantic partners. It means that blood ties, one’s family, come first above all; that loyalty to one’s family is greater than to others to which you’re not related.