Etymology
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-ical 
compound adjectival word-forming element, usually interchangeable with -ic but sometimes with specialized sense (such as historic/historical, politic/political), Middle English, from Late Latin -icalis, from Latin -icus + -alis (see -al (1)). Probably it was needed because the forms in -ic often took on a noun sense (for example physic). Forms in -ical tend to be attested earlier in English than their twins in -ic.
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-ency 

word-forming element denoting quality or state, from Latin -entia. Derivatively identical with -ence; also see -ancy. The slight difference of sense is that -ence can and -ency cannot mean "an act of ____."

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-fuge 
word-forming element meaning "that which drives away or out," from Modern Latin -fugus, with sense from Latin fugare "to put to flight" (see febrifuge) but form from Latin fugere "to flee" (see fugitive (adj.)).
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-one 
chemical suffix, from Greek -one, female patronymic (as in anemone, "daughter of the wind," from anemos); in chemical use denoting a "weaker" derivative. Its use in forming acetone (1830s) gave rise to the specialized chemical sense.
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-eroo 
"factitious slang suffix" (OED), sometimes affectionate, forming nouns indicating "a humorous or remarkable instance" of what is indicated, in use by 1940s, perhaps from buckaroo. An earlier suffix in a similar sense is -erino (after 1900), apparently from -er + Italian suffix -ino.
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-path 
word-forming element used in modern formations to mean "one suffering from" (a disease or condition), from Greek pathos "suffering" (from PIE root *kwent(h)- "to suffer"). Also "one versed in" (a certain type of treatment), in which cases it is a back-formation from -pathy in the related sense.
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cyto- 
before a vowel, cyt-, word-forming element, from Latinized form of Greek kytos "a hollow, receptacle, basket" (from PIE *ku-ti-, from root *(s)keu- "to cover, conceal"); used in modern science since c. 1859 for "cell," perhaps especially from the sense (in Aristophanes) of "a cell of a hive of wasps or bees."
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lepido- 
before vowels lepid-, word-forming element used since late 18c. in science with a sense of "scale" (of a fish, etc.), combining form of Greek lepis (genitive lepidos) "scale of a fish" (related to lepein "to peel;" see leper). As in lepidodendron (1819 in German), common fossil "club-moss tree" of the Carboniferous.
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neo- 

word-forming element meaning "new, young, recent," used in a seemingly endless number of adjectives and nouns, mostly coined since c. 1880, from Greek neos "new, young, youthful; fresh, strange; lately, just now," from PIE root *newo- (see new). In the physical sciences, caeno-, ceno- is used in the same sense. Paleo- is opposed to both.

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-phile 
also -phil, word-forming element meaning "one that loves, likes, or is attracted to," via French -phile and Medieval Latin -philus in this sense, from Greek -philos, common suffix in personal names (such as Theophilos), from philos "loving, friendly, dear; related, own," related to philein "to love," which is of unknown origin. According to Beekes, the original meaning was "own, accompanying" rather than "beloved."
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