1) Careless 2) Casual 3) Characterized by neglect 4) Disregardful 5) Failing in what duty requires 6) Forgetful 7) Inattentive 8) Leaving vulnerable 9) Neglectful of 10) Oblivious 11) Rash 12) Reckless 13) Remiss 14) Slack 15) Slipshod 16) Unmindful 17) Unprotective 18) Without regard 1) Careless 2) Disregardful 3) Negligent 4) Remiss 5) Unprotective 
• (a.) Full of neglect; heedless; careless; negligent; inattentive; indifferent. • (a.) Full of neglect; heedless; careless; negligent; inattentive; indifferent.
Neg·lect'ful adjective Full of neglect; heedless; careless; negligent; inattentive; indifferent. Pope. « A cold and neglectful countenance.» Locke. « Though the Romans had no great genius for trade, yet they were not entirely neglectful of it.» 
[adj] - leaving vulnerable
neglectful 1. Not showing due care or attention. 2. Characterized by neglect; disregardful; careless; negligent.
characterized by neglect; disregardful; careless; negligent (often fol. by of&hasp;): neglectful of one's health.