(Greek > Latin: suffix; from French -aque, or directly from Latin -acus, from Greek -akos forming adjectives. This suffix was used to form names of arts and sciences in Greek and it is now generally used to form new names of sciences in English; meanings, "related to, of the nature of, pertaining to, referring to")

The suffix -ic has related elements.

ambrosiac (adjective), more ambrosiac, most ambrosiac
Originally the food of the gods, thought to confer immortality; delicious; sweet-smelling: An ambrosiac dessert consisting primarily of oranges and flaked coconut is totally delectable.

The perfume that Catherine uses has a most ambrosiac odor.

ammoniac (s) (noun) (no pl)
Relating to the resin extracted from the stem of the herb Dorema ammoniacum: Ammoniac is quite strong-smelling and was formally used as a stimulant, as a perfume, or even used in cement for porcelain.
ammoniac (adjective), more ammoniac, most ammoniac
Pertaining to ammonia, a gaseous compound consisting of nitrogen and hydrogen: When Jane opened the jar, she couldn't breathe in because of the ammoniac smell that escaped from the inside.
amnesiac (s) (noun), amnesiacs (pl)
Someone who is afflicted with a partial or a total loss of memory: Amnesiacs and their conditions are usually results of shocks, psychological disturbances, brain injuries, illnesses, etc.
anaphrodisiac (adjective), more anaphrodisiac, most anaphrodisiac
Relating to something which decreases sexual desires: In order to safely transport the stallion with the other horses, John, the veterinarian, gave him an anaphrodisiac injection.
anthomaniac (s) (noun), anthomaniacs (pl)
Someone who has an abnormal passion for flowers or who is intensely fond of various blossoms: When she planned on moving, Lois, known to be an anthomnaniac, only wanted to have a house with a large garden and cultivate it with many assorted kinds of flowering plants.
antidemoniac (adjective), more antidemoniac, most antidemoniac
Regarding anything effective against evil spirits: Jane decided to plan an antidemoniac protest march to contend against evil supernatural beings that some people still believed in.
aphrodisiac (adjective) (not comparable)
Regarding something that arouses sexual desire: Dorothy thought that if she wore her new sexy nightgown it would have an aphrodisiac effect on her spouse.
aphrodisiac (s) (noun), aphrodisiacs (pl)
A food, drug, potion, or other agent that arouses sexual desire: Susan asked Tom if he knew that strawberries were to be aphrodisiacs and enhance their erotic life!
cardiac (adjective) (not comparable)
Near or relating to the heart: In Joan's book, all of the patients in hospital were suffering from cardiac weaknesses.

When Arthur went to see Dr. Smith, a cardiac exam was performed, and the doctor listened to his heart and and took his pulse.

cardiac (s) (noun), cardiacs (p)
1. A person who suffers from a heart disease: All the cardiacs on the ward in hospital needed to have rest and quiet.
2. A drug used to stimulate the heart muscle: The medicine that Stella's old grandfather used to take was a cardiac to vitalize the muscle in the circulatory organ in his body.
celiac, coeliac (adjective) (not comparable)
1. Relating to the region of the abdomen or abdominal cavity: Dr. Thompson still had to find out the reason for Frank's celiac ailment, and so Frank had to stay in hospital a bit longer for all the different tests to be made.
2. Pertaining to an abdominal disease: Because Floyd was having pain in his stomach, he went to his doctor who prescribed a celiac diet to relieve his disorder.
demoniac (s) (noun), demoniacs (pl)
An individual who is dominated by an evil spirit: Jane's sister seemed to be a demoniac, possessed by the devil, and certainly acted like one!
demoniac (adjective), more demoniac, most demoniac
1. Regarding a person or an animal believed to be possessed by an evil spirit: In the ghost story Wendy was reading, the main character was influenced by a demoniac being.
2. Feverish, frenzied, frantic: Just before Ruth was to get married, she was very busy in a demoniac way with tons of errands to do and decisions to make.
elegiac (adjective), more elegiac, most elegiac
1. Pertaining to a woeful poem: The verse Mrs. Smart read to her class at school was very elegiac and gloomy and made all the students quite sad.
2. Referring to the communication of sorrow, sadness, or morning: The music played at the funeral was certainly elegiac and made many people cry.