The ability to define a word with accuracy and precision is an important skill that has been associated with academic achievement. This study investigated the feasibility of conducting a lesson on formal word definitions to improve children's definitional production. The participants were 18 children in grade 4 (mean age: 9 years; 8 months) who were delayed readers by one grade level. Initially, the children wrote definitions for high- and lower-frequency nouns and verbs. Subsequently, a definitional lesson was delivered, which focused on the formal structure of noun and verb definitions and accuracy/precision of meaning. Lastly, the children were given a written post-test, which also contained high- and lower-frequency nouns and verbs. Words were controlled for frequency, imageability, difficulty, and familiarity. Noun and verb definitions were coded and scored for level of structure (form). Nouns were coded and scored for content (expressed meaning). Results indicated that post-test scores were significantly higher for form for nouns and verbs. For content, noun scores were significantly higher in post-test. Findings indicated that a one-time lesson on formal definitional production can positively influence children's definitions. Limitations of the study and future research ideas are discussed. (Contains 8 tables.)