In contemporary linguistics, subordination and coordination are most commonly used in syntax, with co-ordination referring to independent clauses, and subordination to the dependent ones. In this paper, we approach the phenomenon of coordination from the syntagm point of view with the aim of describing the relation between the syntagm and the word. For the purpose of this analysis, “word” is understood as an orthographic unit (a language unit written between two blank spaces) which is, in addition, in the sense of derivational morphology, a compound with at least two stems. In this respect, the most challenging are the derivation of semi-compounds, in the traditional sense, and the understanding of the function of a dash. The dash conveys two senses: formal (orthographic and derivational) and the semantico-syntactic. The formal function refers to the connection of at least two constituents (stems), while the semantico-syntactic function relates, on one hand, to the subordination (connecting parts of the word, i.e., one stem appears as superior to others; also called single-term compound), and on the other hand, to the coordination (connecting two or more words, i.e., the stems of the equal level; multi-term compounds). A similar problem occurs with respect to the compounds which are formally of the same status as the syntagm or the word phrase from which they have been derived. In this paper, the mentioned derivational-morphological problem is explored from the perspective of orthographic diachrony: we analyse the approaches in Croatian orthography books that mirror the concept of coordination at the syntagm and word level (i.e., a compound consisting of at least two stems). Our analysis includes all parts of speech, with the goal of listing, describing and scientifically explaining all the questionable cases.