Go to 'thermo-' entry Go to 'dino-' entry Go to 'chondro-' entry Go to 'aero-' entry Go to '-logy' entry Go to 'thaumato-' entry Go to 'nano-' entry Go to '-sophy' entry Go to 'bucco-' entry Go to '-ism' entry Go to '-lysis' entry Go to 'galacto-' entry Go to '-anthropy' entry Go to 'pneumo-' entry Go to '-ploitation' entry Go to '-lithic' entry Go to '-sepalous' entry Go to 'onco-' entry Go to '-parous' entry Go to 'dermato-' entry Go to 'multi-' entry Go to 'dodeca-' entry Go to '-zoon' entry Go to 'vermi-' entry Go to 'crystallo-' entry Go to 'biblio-' entry Go to 'eco-' entry Go to 'juxta-' entry Go to 'facio-' entry
Affixes: the building blocks of English
Affixes: the building blocks of English

-ac Also -acal.

Forming adjectives and nouns.

[Latin -acus or French -aque from Greek -akos.]

All words ending in -ac from this source include an i from the original Latin or Greek root, so making it in effect -iac.

Some are adjectives: cardiac (Greek kardia, heart), of the heart; iliac (Latin ilia, entrails), relating to the ilium, a bone in the pelvis, or to the nearby regions of the lower body. Others are nouns: aphrodisiac, a food, drink, or drug that stimulates sexual desire; zodiac, the belt of the heavens that includes the apparent paths of the sun, moon, and principal planets. Some can be both noun and adjective: amnesiac, hypochondriac, insomniac.

Nouns often have linked adjectives in -al (see -al1), as in zodiacal and ammoniacal. In a few cases, adjectives in both forms co-exist, as with paradisiac and paradisiacal, or heliac and heliacal (though in both these cases the form in -acal is much more common).

Some words in -ac have related forms in -ic: demoniac and demonic, haemophiliac and haemophilic, maniac and manic. In each of these cases the form in -ic is an adjective, irrespective of the role of the form in -ac. An exception is amnesiac, in which amnesic can be both adjective and noun.

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