Oct 22, 2014

Demystifying Nouns in Wordnet

WordNet is an excellent resource for all sorts of NLP tasks. Having said that, understanding some of the relationships between terms can be quite difficult. For example, when you are searching for a noun, you are faced with all sorts of relationships such as holonyms, meronyms, hyponyms and meronyms when all that you are looking for is just plain synonyms. In this article, I am going to try to explain some of the relationships for nouns. Please note that this is not WordNet specific, this is more about understanding some basic linguistics.

Relationships in WordNet

  • For nouns: Antonym, Hypernym, Instance Hypernym, Hyponym, Instance Hyponym, Member holonym, Substance holonym, Part holonym, Member meronym, Substance meronym, Part meronym, Attribute, Derivationally related form , Domain of synset (topic, region, usage), and Member of this domain (topic, region, usage). 
  • For verbs: Antonym, Hypernym, Hyponym, Entailment, Cause, Also see, Verb Group, Derivationally related form, and Domain of synset (topic, region, usage). 
  • For adjectives: Antonym, Similar to, Participle of verb, Pertainym (pertains to noun), Attribute, Also see and Domain of synset (topic, region, usage).
  • For adverbs: Antonym, Derived from adjective, and Domain of synset (topic, region,usage)

Hyponyms and Hypernyms

Hyponyms: a word or phrase that is a more specific than the given word.
Hypernyms: a word or phrase that is a more general than the given word. 
Hyponyms have a direct relationship with hypernyms where hyponym is the specific term and hypernym is the more general term. Let us take the word 'limb' as an example. What is more specific than limb?
  • arm is a kind of limb
  • leg is a kind of limb

So in this case 'arm' and 'leg' are the hyponyms and 'limb' is the hypernym because arm and leg are the more specific terms in this relationship. Here is a list of hyponyms from WordNet for 'limb' in the human limb sense:
hind limb -- (a posterior leg or homologous structure in other animals)
forelimb -- (the front limb (or homologous structure in other animals such as a flipper or wing))
flipper -- (the flat broad limb of aquatic animals specialized for swimming)
leg -- (a human limb; commonly used to refer to a whole limb but technically only the part of the limb between the knee and ankle)
crus -- (the leg from the knee to foot)
leg -- (a structure in animals that is similar to a human leg and used for locomotion)
thigh -- (the part of the leg between the hip and the knee)
arm -- (a human limb; technically the part of the superior limb between the shoulder and the elbow but commonly used to refer to the whole superior limb)
cubitus -- (the arm from the elbow to the fingertips)
forearm -- (the part of the superior limb between the elbow and the wrist)
Wikipedia article: http://en.wikipedia.org/wiki/Hyponymy_and_hypernymy


Meronyms: something that is part of a larger thing. Let us take arm as an example. What is part of an arm?
  • bicep is part of an arm
  • wrist is part of an arm
Here is a list of meronyms from WordNet for 'arm' in the human limb sense:
HAS PART: brachial artery, arteria brachialis 
HAS PART: cephalic vein, vena cephalica 
HAS PART: forearm
HAS PART: hand, manus, mitt, paw
HAS PART: ulnar nerve, cubital nerve, nervus ulnaris
HAS PART: biceps brachii, musculus biceps brachii, biceps humeri
HAS PART: triceps brachii, musculus triceps brachii 
HAS PART: elbow, elbow joint, human elbow, cubitus, cubital joint, articulatio cubiti 
HAS PART: wrist, carpus, wrist joint, radiocarpal joint, articulatio radiocarpea 
HAS PART: arm bone
HAS PART: humerus
Wikipedia article: http://en.wikipedia.org/wiki/Meronymy


Holonym: a word that represents the physical whole of a given word. Basically, the opposite of meronyms. Let us take the same arm as an example. What is an arm a part of?
  • an arm is part of a body
  • an arm is part of a human being 
Here is a list of holonyms from WordNet for 'arm' in the human limb sense:
PART OF: body, organic structure, physical structure 
PART OF: homo, man, human being, human 
Here is another example, for the word 'toe'. What is a toe a part of? 
  • a toe is part of a human foot