Investigating Lexical Density and Cohesion in Igbo Academic Writing: Evidence from University Undergraduate Theses

This study investigates lexical density and cohesive device deployment in Igbo academic writing, drawing on a corpus of one hundred undergraduate theses written in Igbo language by students in Igbo language departments at four universities in South East Nigeria. Igbo academic writing as a specialised register is shaped by competing pressures from oral tradition rhetorical conventions, English academic writing influence, and emergent Igbo scholarly writing norms, yet its textual linguistic properties have not been empirically characterised. Lexical density is measured using the standardised formula of lexical items per total running words, while cohesive analysis examines reference, conjunction, substitution, ellipsis, and lexical cohesion patterns using Halliday and Hasan's cohesion taxonomy. Statistical comparisons are made across thesis chapters and across universities. Findings indicate moderate to low lexical density scores relative to published English academic writing, with a heavy reliance on repetition-based lexical cohesion rather than collocation or hyponymic chaining. Referential cohesion is the most frequently deployed cohesive category, while ellipsis is almost entirely absent, consistent with the expansive oral-derived rhetorical tradition from which Igbo academic writing draws. First chapters demonstrate higher lexical density than methodology and conclusion chapters. The study provides the first systematic register description of Igbo academic writing and proposes implications for academic writing instruction in Igbo language programmes. Keywords: Igbo academic writing, lexical density, cohesion, register analysis, undergraduate theses.