The phrase "Blood is thicker than water" is often used to emphasize the idea that family relationships, specifically those based on shared blood or biological ties, are stronger and more important than other types of relationships or friendships. In essence, it suggests that familial bonds are more significant and should take precedence over other social or personal connections.
The full saying is actually, "The blood of the covenant is thicker than the water of the womb," which has a somewhat different meaning. It implies that the bonds formed through shared experiences, challenges, and commitments (the "covenant") are stronger than mere biological relationships (the "water of the womb"). So, in its original form, it encourages valuing chosen relationships and connections as highly as, or even more than, family bonds. However, over time, the phrase has been shortened to convey the opposite idea, emphasizing family over other relationships.