Compound of heteros ('different/other') and didaskaleo ('to teach'). Heterodidaskaleo means to teach a doctrine different from the apostolic standard — to propagate heterodoxy.
Paul uses heterodidaskaleo in 1 Timothy 1:3 as he urges Timothy to 'charge some that they teach no other doctrine.' This compound word encapsulates the Pastoral Epistles' central concern: false teaching is not merely academic error — it damages souls, corrupts the church, and ultimately denies the gospel. The 'different teaching' (hetero-doctrine) is contrasted with the hygiainouses didaskalia ('sound/healthy doctrine') of the apostolic pattern. Theological precision matters because doctrine shapes life. Those who heterodidaskaleo do not 'consent to wholesome words' and are 'proud, knowing nothing' (1 Tim. 6:3–4).