benign, malign

1. benign - not dangerous to health; not recurrent or progressive (especially of a tumor)

pathology - the branch of medical science that studies the causs and nature and effects of diseases

malignant - dangerous to health; characterized by progressive and uncontrolled growth (especially of a tumor)

2. benign - pleasant and beneficial in nature or influence; 

"a benign smile"; "the benign sky"; "the benign influence of pure air"

benignant

harmless - not causing or capable of causing harm; "harmless bacteria"; "rendered the bomb harmless"

kind - having or showing a tender and considerate and helpful nature; used especially of persons and their behavior; "kind to sick patients"; "a kind master"; "kind words showing understanding and sympathy"; "thanked her for her kind letter"

malign - evil or harmful in nature or influence; "prompted by malign motives"; "believed in witches and malign spirits"; "gave him a malign look"; "a malign lesion"

3. benign - kindness of disposition or manner; 

"the benign ruler of millions"; "benign intentions"

kind - having or showing a tender and considerate and helpful nature; used especially of persons and their behavior; "kind to sick patients"; "a kind master"; "kind words showing understanding and sympathy"; "thanked her for her kind letter"

1. malign - evil or harmful in nature or influence; 

"prompted by malign motives"; "believed in witches and malign spirits"; "gave him a malign look"; "a malign lesion"

maleficent - harmful or evil in intent or effect

harmful - causing or capable of causing harm; "too much sun is harmful to the skin"; "harmful effects of smoking"

unkind - lacking kindness; "a thoughtless and unkind remark"; "the unkindest cut of all"

benignant, benign - pleasant and beneficial in nature or influence; "a benign smile"; "the benign sky"; "the benign influence of pure air"

2. malign - having or exerting a malignant influence; 

"malevolent stars"; "a malefic force"

malefic, malevolent, evil

maleficent - harmful or evil in intent or effect

.... http://www.thefreedictionary.com/malign