This study would like to investigate the structures and meanings of Vietnamese words with focusing on compound words, which is the most productive way to form words. Thus, it aims to provide an under standing on formation of Vietnamese compound words. The Vietnamese language is identified as the monosyllabic language. That is, the smallest unit of the word is a morpheme, or a morphemsyllable to be exact. When morpheme become the basic components of the word and have the structural, semantic relationships with each other, it turns out to be compound words . Compound words are distinguished from repetitive words, Tu Lay, and also different from idioms. Phrases may look similar to compound words in the syntactic sense, but are different semantically. The syntactic construction of Vietnamese compound words can be categorized by three types: 1) composing two free morphemes, 2) consisting of one free morpheme and one bound morpheme, 3) forming two bound morphemes. There seem no phonic changes, no continuing use, or no hyphens when the compound words are formed. This demonstrates the linguistic characteristics of the Vietnamese language, which is a syllabic language. In addition to these syllabic features, there is no limitation on combination of Vietnamese original words with Tu Han Viet, Vietnamese Chinese words. This study also explores the semantics of compound nouns, based on the semantic relationship of components: synonymy, antonymy, and meronomy. Compound nouns in synonymy become surplus in structures but represent more decent meanings. The second type, those in antonymy, has the same, integrated or categorized meanings of each antonym. Compound nouns in meronomy become to have the meaning of sub categories of each meronomy, based on its internal semantic features.