A reading experiment combining online and offline data evaluates the effect on second language learners' reading behaviors and lexical uptake of three gloss types designed to clarify word meaning. These are (a) textual definition, (b) textual definition accompanied by picture, and (c) picture only. We recorded eye movements while intermediate learners of English read a story presented on-screen and containing six glossed pseudowords repeated three times each. Cumulative fixation counts and time spent on the pseudowords predicted posttest performance for form recall and meaning recognition, confirming findings of previous eye-tracking studies of vocabulary acquisition from reading. However, the total visual attention given to pseudowords and glosses was smallest in the condition with picture-only glosses, and yet this condition promoted best retention of word meaning. This suggests that gloss types differentially influence learners' processing of novel words in ways that may elude the quantitative measures of attention captured by eye-tracking.