Tonal Autonomy in Igbo colour Ideophones

This paper examines the tonal organisation of colour ideophones in Igbo, arguing that they constitute a morphophonologically autonomous class that cannot be derived through the productive tonal alternation rules identified by Uchechukwu (2004, 2011) for sound and emotion ideophones. The study adopts a qualitative, descriptive and corpus-based research design. The data comprise eleven colour ideophones compiled from published lexicographic sources and grammatical descriptions, each annotated for citation-form tone melody and etymological source. The data were analysed in three steps: (i) classification and frequency count of the attested tone melodies; (ii) identification of the etymological source of each form and comparison of the source tone with the ideophone tone; and (iii) evaluation of a productive-alternation hypothesis against a lexical-specification hypothesis, using three diagnostics, namely tonal heterogeneity, tonal stability under reduplication, and etymological tone retention. The analysis shows that at least three distinct tone melodies are attested (L-H, H-L, and H-H), a distribution incompatible with a uniform ideophonic tone template. The paper proposes two complementary arguments: (1) an extension of Uchechukwu's sensory tier framework that positions colour ideophones as occupying a distinct perceptual-cultural tier from sound and emotion ideophones; and (2) a lexical tonology analysis showing that colour ideophones bear lexically specified tones inherited from or motivated by etymological source forms, rather than tones derived through productive alternation rules. Together, these arguments predict tonal heterogeneity as a principled consequence of the symbolic rather than iconic grounding of colour ideophony in Igbo. The findings have implications for the crosslinguistic typology of ideophonic tone and for models of sensory encoding in the Igbo lexicon.