lacking

The word “lacking” means missing, or not having enough of something needed. In plain terms, missing something, or falling short of what's needed.

“Lacking” is pronounced LA-kihng (/ˈlækɪŋ/ in IPA).

Here is “lacking” used in a sentence: “The report was lacking in detail and had to be rewritten.”

The opposite of “lacking” — its antonyms — is present.

“Lacking” is an adjective.

“Lacking” is a fairly common word in modern English.

Both are correct. "Lacking confidence" treats lacking like a verb form taking a direct object, while "lacking in confidence" uses the adjective pattern with "in", which is slightly more common when describing character and qualities. The meaning is identical: not having enough of something needed.

"Missing" means simply not there: a missing page is absent. "Lacking" adds the idea of insufficiency against a need or standard: something can be present but still lacking if there is not enough of it, as in "the evidence was lacking". Use missing for absence and lacking for shortfall.

Both mean not having enough of something needed. "Deficient" is more formal and technical, common in medical, nutritional, and official contexts such as "deficient in iron", and often implies measurement against a defined requirement. "Lacking" is the everyday choice and can describe anything from resources to confidence.