Bias
Etymology
From French "biais" (slant, oblique), of uncertain deeper origin. The word entered English through the game of lawn bowls, where a "bias" was the weight built into the ball that made it roll in a curve rather than straight — the perfect image of a consistent, built-in deviation.
noun · /BY-us/
A systematic slant in judgment or measurement that pushes results consistently in one direction.
What it names
Error with a pattern — the crucial distinction from random noise — which is why bias, unlike a one-off mistake, can be predicted and corrected.
Example
The survey’s wording introduced a bias that made support look ten points higher than it was.
Related idea
Bias is a consistent deviation in one direction; a fallacy is a flaw in the logic of an argument — you can reason validly from biased data, or reason fallaciously from clean data.
noun · /BY-us/
A line running diagonally across the grain of a woven fabric; cloth cut along it drapes and stretches in a way straight-cut cloth cannot.
What it names
the diagonal direction across cloth
Example
The gown was cut on the bias so it clung and flowed with every movement.
Related idea
The bias cut is prized precisely for its elegance — an effect achieved by the economy of a single diagonal.