-logy

Etymology

It is inherited from Middle English -logie,^[2][3] borrowed from Old French -logie and its source borrowed from Latin -logia,^[3][4][5][6] from Ancient Greek -λογία (-logía), as in θεολογία (theología).^[3][6] The Greek ending is built partly on λόγος (lógos, “word, speech, discourse”) and partly on the stem of λέγω (légō, “to speak”),^[5][6][4] with the noun suffix that gave -y.^[2][7] The verb goes back to Proto-Indo-European *leg- (“to collect, gather”), with speaking understood as picking out words.^[4] It is related to logos and legend.^[6][8]

Earliest recorded meaning

It was at first simply the ending of words adapted from Greek, the earliest of which, such as theology, came through French.^[3] Its Greek senses were of two kinds: a way of speaking, as in eulogy and tautology, and the study pursued by someone called -λόγος (-lógos), as in ἀστρολόγος (astrológos).^[5][6]

Semantic evolution

Since the first element of a name of a study is usually a noun that ends in -o- in combination, the regular form is -ology; mineralogy is an exception.^[5] New names of sciences imply matching adjectives in -logical and agent nouns in -logist.^[5] A separate sense of a collection goes back to Greek words such as anthology, and Collins adds a body of writings, as in trilogy and martyrology.^[6][8] Merriam-Webster also lists a discourse or treatise, as in insectology.^[2]

Timeline

• 1362 – theology.^[3]
• 1387 – astrology.^[3]
• 1555 – tautology, a way of speaking.^[3]
• 1621 – anthology, a collection.^[3]
• 1686 – biology.^[3]
• 1731 – geology.^[3]

Meanings

Suffix

1. Forming names of a science, study or body of doctrine: musicology, sociology.^[8][2][6]
2. Forming nouns for speech, writing or a way of expression: phraseology, eulogy.^[2][6][8]
3. Forming nouns for a collection or set of written works: anthology, trilogy.^[6][8]

Word family

• analogy
• apology
• eulogy
• haplology
• tetralogy
• trilogy
• biology
• geology
• theology
• technology

Related words

• -logic
• ology
• -ology
• -logist
• logos
• bio-

Usage notes

Words in -logy are normally stressed on the syllable before the suffix, as in biology.^[9]

References

1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
2. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
3. ^ a b c d e f g h i j Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
4. ^ a b c Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
5. ^ a b c d e Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
6. ^ a b c d e f g h i Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
7. ^ Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
8. ^ a b c d e Collins English Dictionary (2023), Glasgow: HarperCollins
9. ^ Jones, Daniel (2011), Cambridge English Pronouncing Dictionary, 18th ed., ed. Peter Roach, Jane Setter and John Esling, Cambridge: Cambridge University Press