What is a good synonym for "attribute"?

Solution 1:

Given the examples you provide, I reckon spec would be a pretty darn good option.

Solution 2:

Trait, characteristic, property.

Also: point, marker.

Solution 3:

It really depends on the context as much as the audience. In computing, for example, we struggle quite a bit to give each of these terms an unambiguous space of its own. Try conflating the words trait, attribute, property, facet and aspect in a software design discussion, for example. You'll get some frowns, I'm sure.

"Facet" and "aspect" are two words not yet given that have their own shortcomings, as does "factor." I can't think of a memorable short word in the sense you want that doesn't bring some baggage with it. Personally I'd choose "trait" and take my chances.

Solution 4:

"Feature" is an appropriate synonym, although, depending on your audience, that may cause confusion due to the prevailing connotation of "positive attribute". Strictly by the word's denotation though, "feature" could be dropped into each of those sentence fragments.

Another synonym is "trait". That has the advantage of having fewer popular connotations to muddy its meaning, but the disadvantage of being (I think) a less common word and may cause confusion in some audiences as to its denotation.

Solution 5:

Feature, quality? Depends on the acception you want to express.

In your examples they don't fit the color one, in my opinion.