Lexical-syntactical analysis is the study of the meaning of individual words (lexicology) and the way those words are combined (syntax) in order to determine more accurately the author’s intended meaning.
Virkler & Ayayo, Hermeneutics: Principles and processes of Biblical interpretation, p. 98 (2nd ed. 2007).
Essentially, it's looking at the individual words (Lexical) and their usage (Syntactical) in order to determine the original meaning (Analysis).
The different components of lexical-syntactical analysis, per here are:
- Identify the general literary form
- Reconstruct the development of the author's theme and how a passage fits into the context
- Identify the natural divisions of the text
- Identify the connecting words within paragraphs and sentences
- Identify points of comparison, contrast and conclusion
- Determine what the individual words mean
- Analyze the relationship between words (syntax)
- Summarize your results into an easily understood synopsis that clearly conveys the author's meaning
A (possibly dramatic) simplification of this would be:
- Determine the meaning of each word (Lexicon)
- Examine the relationship between the words (Syntax)
- Analyze the words in the context of the sentence.
Interestingly, it seems to be used frequently for programming languages as well.