Only full-length words should appear in a dictionary is not a correct statement.
Step-by-step explanation:
Generally in a dictionary some word consists of full-length definition. So to understand the significance of the word brief clarification is required. Sometimes dictionaries often include abbreviations when they mention the part of speech of a particular word. In the Second Edition of the 20-volume Oxford English Dictionary contains full passages for 171,476 words in current use and 47,156 outdated words. This might be included around 9,500 subsidiary words included as subentries.