Abstract

Second language (L2) vocabulary knowledge comprises two complementary dimensions: breadth, referring to the number of words a learner knows, and depth, referring to the richness and complexity of knowledge associated with each word. Vocabulary depth acquisition is a gradual, multidimensional process in which receptive knowledge typically precedes productive knowledge, and the form–meaning link constitutes the most basic and accessible component of lexical knowledge. Research on L2 vocabulary depth has mainly focused on Indo-European languages, showing that inflectional and derivational morphology are among the most challenging aspects. Far less is known about Semitic languages, where root-and-pattern morphology shapes lexical processing. In Hebrew, the developmental patterns of productive vocabulary depth across meaning and use remain unclear, and it is uncertain whether lexical difficulty hierarchies observed in Indo-European languages extend to Semitic contexts.

Thirty high-frequency Hebrew words were assessed among 34 Arabic-speaking learners of Hebrew through a recall-based discrete-point test (180 items, yielding 6,120 responses) across five aspects: definitions, synonyms, antonyms, inflections (gender, number, person), and phraseology.

The study revealed a clear hierarchy of difficulty in productive vocabulary depth knowledge. Learners exhibited high accuracy in tasks requiring basic definitional knowledge (87.65%), followed by inflections of number (77.75%) and gender/person (70.59%). In contrast, performance was significantly weaker in tasks demanding nuanced lexical knowledge, with accuracy rates dropping to 44.31% for antonyms, 33.24% for phraseology, and 29.90% for synonyms. Pairwise comparisons showed significant differences across most vocabulary-depth knowledge aspects, except synonyms and phraseology.

The results highlight uneven development in productive vocabulary depth knowledge, with meaning recall and morphology more accessible than semantic associations and phraseological knowledge. They extend lexical depth hierarchy research beyond Indo-European contexts, underscoring both universal and language-specific patterns in L2 lexical development.