pass-, pati- +

1. Incapable of suffering.
2. Inaccessible to harm or pain.
3. Not to be touched or moved to passion or sympathy.
4. Unfeeling, or not showing feeling.
5. Without sensation.
6. Not susceptible to or not capable of feeling physical pain or injury.

1. Exemption from pain or suffering.
2. Not subject to injury from external things.

Incapable of feeling emotion or of experiencing pain.

To fill with passion; to arouse emotionally; to inflame with intense feeling; to infuse passion into; to stir the passions or feelings of; to excite deeply or strongly.

Did you notice that the im- prefix of impassion and impassioned are intensive while the im- prefix used with the previous word (impassionate) has the meaning of “no, not, lacking,” etc.? It shows that one can not depend on these prefixes to mean the same thing for all words.

Not too many years ago, just about every gasoline truck in the U.S. had large signs painted on them that said, INFLAMMABLE. Since most people thought that the prefix in- meant “not”, they interpreted INFLAMMABLE to mean NOT FLAMMABLE. Now the trucks carry the painted signs: FLAMMABLE to eliminate any confusion.

The Family Word Finder, a Reader‘s Digest publication, says, “Flammable has now replaced its older synonym inflammable [from Latin inflammare, to kindle) in technical and commercial usage, where the word FLAMMABLE on a dangerously combustible product is thought to serve as a more unmistakable warning.”

1. Without feeling or passion; calm, dispassionate.
2. Free from, or not governed by, passion; calm, dispassionate.

1. Filled with passion; having or showing strong feeling.
2. Implies warmth and intensity without violence and suggests fluent verbal expression.
3. Ardent, as an impassioned oration; fervent, fiery, stirring.

1. Not feeling pain; not feeling or showing emotion.
2. Expressionless, unresponsive to something that might normally excite interest or emotion.
3. Insensible, unconscious; placid, serene, calm, unperturbed; apathetic.
4. Deprived of feeling or sensation; insensible, unconscious.

In an impassive manner: "She submitted impassively to her own arrest by the police officer."

1. Lacking patience; the inability to bear suffering; discomfort and annoyance with calmness or composure; passionate, ardent, anxious.
2. Failure to bear suffering, discomfort, annoyance, etc. with equanimity; irritability, irascibility.

1. Feeling or showing a lack of patience; feeling or showing annoyance because of delay, opposition; agitation, irritable.
2. Showing or feeling restless eagerness to do something, go somewhere; overzealous, hasty.
3. Not patient; not bearing or enduring (pain, discomfort, opposition, etc.) with composure.
4. Lacking endurance; irritable, irascible, easily provoked.

1. In an impatient manner.
2. With uneasiness or restlessness; such as, to bear disappointment impatiently.
3. With eager desire causing uneasiness; such as, to wait impatiently for the arrival of one's friend.

Having no pity or compassion.

1. Not compatible; unable to exist together in harmony: "She asked for a divorce because of their incompatibility."
2. Contrary or opposed in character; discordant; such as, the incompatibility of colors.
3. That which cannot coexist or be conjoined.
4. A reference to biological substances that interfere with one another physiologically, as different types of blood in a transfusion.
5. In pharmacology, of or pertaining to drugs that interfere with one another chemically or physiologically and therefore cannot be mixed or prescribed together.

1. Not able to exist in harmony or agreement; not going or getting along well together; incongruous, discordant, conflicting, antagonistic, mismatched.
2. Mutually intolerant; incapable of existing together in the same subject; contrary or opposed in character; discordant, incongruous, inconsistent.
3. The incapacity of cells or tissue from one individual to tolerate those of some other individual when an organic union of some kind is formed between them; especially, in grafting and transplantation, in the transfusion of blood, and in parasitism.

1. Without compatibility.
2. Incapable of associating or blending or of being associated or blended because of disharmony, incongruity, or antagonism.