This article is devoted to the problem of terminology in relation to medieval altarpiece monuments of Catalonia. In historiography, one can find the concepts such as ‘antependium’, ‘frontal’, ‘pallium’, and ‘tabula’ being misrepresented. The aim of this study was to separate the above-mentioned terms, to give them an accurate definition, and to choose the most relevant one in relation to Catalan altarpiece paintings. Basing mainly on written medieval sources due to the poor preservation of the altarpiece works of Catalan churches, the author comes to the conclusion that in modern Catalan historiography, there was an erroneous substitution of terms: the term ‘frontal’, most often used in relation to the works of altar painting on wood, should, in fact, be applied exclusively to a certain fragment of textile altar decoration. The author concludes that for the definition of the Catalan wooden panels in front of the altar, the most common, albeit late, term is "antependium". The concept of ‘tabula’ also turns out to be appropriate in the definition of this type of painting, since the ‘tabula’ is the front panel of the altar, made of either precious metal, wood, or stone. The word ‘pallium’, as follows from archival sources, can only be characterized by the textile design of the altar.