علم متن اللغة
Knowledge of the language's words and their established meanings.
Lexical study assists in recognizing gharaba (obscurity or uncommonness). A word may be so unfamiliar that exceptional searching is required to reach its meaning, or its usage may leave an uncertainty that detracts from fasaha.
The discussion also acknowledges a practical qualification: an ordinary lexicon may not exhaustively explain every unusual expression, and broader linguistic investigation can be needed. Lexical study is therefore an important instrument, not a substitute for the entire science of balagha.