Words and Tokens

2.2 Morphemes: parts of words

1. What is a morpheme? What is morphology?
   A morpheme is a minimal meaning-bearing unit of language (cats = cat + plural -s). Morphology is the study of morphemes.
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 37
2. What is the difference between a root and an affix?
   The root is the central morpheme that supplies the main meaning (work in worked); affixes add additional meanings (-ed).
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 37
3. How do inflectional morphemes differ from derivational morphemes?
   Inflectional morphemes are grammatical, play a syntactic role such as agreement or tense (plural -s, past -ed), are productive, often obligatory and predictable in meaning. Derivational morphemes are idiosyncratic, apply to specific word subclasses, usually change the word class, and have less predictable meanings (care → careful → carefully).
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 37
4. What is a clitic? Give examples.
   A morpheme that acts syntactically like a word but is reduced and attached to another word, so it cannot stand alone: English ’ve in I’ve, possessive ’s, French l’ in l’opéra, Arabic b ‘by/with’ and w ‘and’.
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 37
5. What is morphological typology?
   The study of how languages vary in their morphology, i.e. how words break up into parts.
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 38
6. What is the morphemes-per-word dimension of morphological typology?
   A scale from isolating (analytic) languages with about one morpheme per word (Vietnamese, Cantonese), through synthetic languages, to polysynthetic languages where one word can express a whole English sentence (Koryak).

   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 38
7. What is the agglutinative–fusional dimension of morphological typology?
   How easily morphemes can be segmented: agglutinative languages (Turkish) have morphemes with clean boundaries; fusion languages (Russian) have affixes that conflate several categories, e.g. -om in stolom marks instrumental + singular + first declension at once.
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 38
8. Why is the English -s in “She reads” an example of fusion?
   The single suffix means both third person singular and present tense, with no way to divide the meaning between parts.
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 38
9. Are labels like “agglutinative” or “polysynthetic” properties of whole languages?
   More accurately they are general tendencies: a language can use different morphological systems.
   • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 39
10. Why are morphemes not used as a standard for cross-lingual tokenization?
    Morphemes can be hard to define, and many languages have complex fused morphemes that aren’t easy to break into pieces.
    • Jurafsky & Martin, Speech and Language Processing, 3rd ed. draft, ch. 2, §2.2, p. 39