One of the most remarkable aspects of the Korean language which differentiates it from English is that Korean noun phrases, when quantified, obligatorily require classifiers (CL), exemplified by (1):
(1) Haksayng sey-myeng- i iss-ta.
student three-CL-NOM be-DEC.
‘There are three students.’
Since the characteristics and criteria of Korean classifiers have not been precisely defined, the total number of Korean classifiers is not clear. There are about 290 classifiers which have been identified. Some of them appear to be productively used, but some are not (Im, 1991a, b).
Classifiers pose an interesting question for first-language acquisition since they require knowledge of both syntax and semantics. Syntactically, they reflect functional heads of quantifier phrases, whose order and position are fixed. The typical word order of a Korean quantifier noun phrase is [Noun-Quantifier-Classifier], as in (1) (Im, 1991a,b; see also Sohn, 1999 and C. Lee, 2000). There are some other structures of the Korean quantifier noun phrase, but we will not discuss them here.
Semantically, classifiers reflect a language-specific agreement system in semantic features between the head noun and the classifier. Although categorization of features of the Korean classifiers has not been defined clearly yet, features of the Korean classifier system can be organized according to Adams and Conklin's (1973) three basic features of animacy, shape, and function. Also, the Korean classifier system consists of several other specific features, such as honorific and event. The agreement system in semantic features between the noun and the classifier is well developed in Korean.