καθαίρω

From the study of John 15:2

Range of meaning

'To cleanse, purify, clear'. In general Greek it is used for ritual and physical cleansing. In farming it is used for clearing ground or trimming plants: taking away what is useless so that what is useful can thrive. This is the only place the verb appears in the New Testament.

Against the English

Most modern versions say 'prunes', which gets the farming sense right. KJV says 'purgeth', which in 1611 meant 'cleanses'. YLT says 'doth cleanse by pruning it' and keeps both senses. 'Prunes' alone hides the link to v. 3.

How it drifted

Nothing drifted in the Greek. English has simply never had one word that means both 'cleanse' and 'prune'. Since the KJV, 'purge' has narrowed toward 'get rid of' (as in a political purge).

Used elsewhere in the period

Greek farming writers and Philo use the verb for clearing or trimming plants (Philo is commonly cited here by commentators, e.g. Barrett and Brown). The related adjective καθαρός, 'clean', is ordinary purity language in the Septuagint and in John (13:10–11, 'you are clean, but not all of you').