insidiousness

1. 1.

   subtle and cumulative harmfulness (especially of a disease)

   Broaderharmfulness
2. 2.

   the quality of being designed to entrap

   Broaderperfidy

Other forms of insidiousness

plural

insidiousnesses·

Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.

Questions about insidiousness

What does insidiousness mean?

insidiousness means "subtle and cumulative harmfulness (especially of a disease)". That is the primary sense; the word has 2 in total, listed in full on this page.

How many syllables are in insidiousness?

insidiousness has 5 syllables: in-si-di-ou-sness. The stress falls on "di".

Is insidiousness a common word?

insidiousness is banded "Rare" — specialist or archaic — most readers will not have met it. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.