misprision [misprisions](misinterpretation or misunderstanding; an instance of this, see also: misinterpretation; mistake; misunderstanding) noun [UK: ˌmɪ.ˈsprɪ.ʒən] [US: ˌmɪ.ˈsprɪ.ʒən]
underestimate [underestimates](an estimate that is too low) noun [UK: ˌʌn.də.ˈre.stɪ.meɪt] [US: ˈʌn.də.ˈre.stə.ˌmet]