robust: [16] By a series of semantic twists, robust is related to red. It comes ultimately from Indo- European *reudh- ‘red’ (source of English red). This produced Latin rōbus, which was applied to a particular sort of oak tree with reddish wood. The oak being synonymous with strength, rōbus in due course came to mean ‘strength’. This was carried over into the derived rōbustus ‘firm, strong, solid’, from which English gets robust, and also into the verb rōborāre ‘strengthen’, source of English corroborate [16]. => corroborate, red
