Answer: mistake

AnswerCrossword Clue
MISTAKEIt may be costly
MISTAKEExample of fallibility.
MISTAKEEraser's target
MISTAKESlipup
MISTAKEBlunder
MISTAKEGaffe
MISTAKE"Man is Nature's sole ...!": Gilbert
MISTAKEExample of fallibility
MISTAKEBoner
MISTAKEEstimate incorrectly.
MISTAKEFoozle
MISTAKESlip-up
MISTAKEAn "X" may signify one
mistaketo interpret wrongly
mistakefor certain; surely
mistaketo identify, understand, interpret, or regard wrongly
mistakeerror in judgment, action, or belief
MISTAKEFoul-up
MISTAKEError
MISTAKEClinker
MISTAKEGoof
MISTAKE"Oopsy!" evoker
MISTAKE"Happy accident," so to speak
MISTAKEBoo-boo
MISTAKE"Oops!" prompter
MISTAKEOversight
MISTAKECase for an eraser?
MISTAKEHowler
MISTAKESource of learning?
MISTAKESlip
MISTAKESlip.
MISTAKEJupiter's is corrected: Poe's Gold Bug.
MISTAKEAlice makes one after another in Wonderland.
MISTAKEA wrong definition, for instance.