Is it 'brittleness' or 'a brittleness'? Use "brittleness" as an uncountable noun -- "the brittleness of the pipeline," not "a brittleness" or "many brittlenesses."
The pattern: a quality, not a countable thing
The noun form is useful in analytical writing -- a risk memo, a retro doc -- precisely because it names a quality, not a countable thing, so it takes no indefinite article and no plural, the same way "weakness" or "complexity" would.
"The brittleness of the model comes from one optimistic margin assumption" is correct.
"There are three brittlenesses in this model" and "a brittleness of the model" are both wrong -- "brittleness" doesn't take a plural or an indefinite article in this sense.
When you do need to talk about more than one source of fragility, the natural move is to keep "brittleness" singular and uncountable and name the sources separately: "the brittleness of the model comes from two places -- the margin assumption and the retention estimate" rather than "two brittlenesses."
The common mistake: treating it as countable
In analytical writing, treating "brittleness" as a countable noun reads as a grammar slip that undercuts the analytical, precise tone the word is meant to carry. A risk memo that says "a brittleness" loses some of its authority exactly where it's trying to sound most rigorous.
Want to learn "Brittle" in depth?
Lyra Practice teaches advanced non-native professionals the nuance of high-value expressions like this one, then has you practice using them in realistic work scenarios.
Start learning for free →The fix is simple: reach for "the brittleness of X" or "some brittleness in X" whenever you're tempted to count it, the same instinct you'd already apply to a word like "fragility" or "complexity."
Practice scenarios
Practice using brittle in situations like:
- writing "the brittleness of the pipeline" correctly in a risk memo or retro doc
- catching "a brittleness" before it goes into an analytical document
- describing multiple sources of fragility without pluralizing "brittleness" itself
Useful practice phrases:
- "The brittleness of [X] comes from [dependency]."
- "There's some brittleness in [X], mainly from [cause]."
- "[X] has two sources of brittleness: [A] and [B]."