Remiss

Part of speech: noun (n.)

The act of being remiss; inefficiency; failure. [Obs.] "Remisses of laws." Puttenham.

Part of speech: adjective (a.)

Not energetic or exact in duty or business; not careful or prompt in fulfilling engagements; negligent; careless; tardy; behindhand; lagging; slack; hence, lacking earnestness or activity; languid; slow. Thou never wast remiss, I bear thee witness. Milton. These nervous, bold; those languid and remiss. Roscommon. Its motion becomes more languid and remiss. Woodward.

Synonyms: Slack; dilatory; slothful; negligent; careless; neglectful; inattentive; heedles; thoughtless.