From ancient days, there were many controversies over whether a bird called Jeogu(저구) in the Volume of Gwanjeo(관저편), the first part of “the Book of Odes(시경)”, is a ferocious raptor (osprey) or a friendly raptor (a sort of wild duck). Because the Jeogu(저구) in the first verse of this poem is a symbol of ‘an elegant lady’ who will be an excellent spouse of a noble man, so whether this Jeogu(저구) is viewed as a bird of osprey or a sort of duck is an important key to understand the true meaning of four phrases in the first chapter of the Volume of Gwanjeo(관저편).
 This paper attempts to identify the substance of the name Jeogu(저구) which has been confused or misunderstood over a long period of time, focusing on Three Books of Article Names - Wordbook of Things(재물보), Book of Article Names(물명고), Encyclopedia of Objects(광재물보) -, which emerged in the era when the study of names, objects, law, and numbers(명물도수) was prevalent in the late Joseon Dynasty.
 When examining Chinese classics, it is understood that the confusion regarding the substance of “Jeogu(저구)” originated from the annotation of “Mosijuso(모시주소)”. The views of Chinese scholars views on the substance of ‘Jeogu’ have been debated for a long time, largely divided into one theory called a raptor and another theory called a sort of duck. It is understood that Three Books of Article Names adopted a raptor theory, a duck theory or a theory of the same name for different birds, depending on the type of Three Books of Article Names or by the classification of headwords from each Book.
 From the viewpoint of today's standards, ‘Jeogu’ is an osprey[鶚], which is a raptor. If so, when interpreting the Book of Odes(시경), it is necessary to consider ‘摯而有別’ in Mojeon(모전) as 'it is fierce but it is good at discerning the mate (in terms of chastity).
 Also, it was revealed that Jing-gyeong-yi(징경이, fish hawk), which traditionally referred to as “Jeogu(저구)”, originally indicated to a class of ducks called ‘Mandarin ducks’, but in modern times it has been misinterpreted as an osprey.
 It is thought that the main cause of the constant confusion of the name of an object is usually misunderstanding and miswriting of the object. Due to the misunderstanding and miswriting, the confusion of objects has always been repeated or reproduced. Therefore, when encountering classics, it is necessary to pay attention to the above fact and to take a careful approach.