I.down1[美 daʊn, 英 daʊn]副down often appears as the second element of certain verb structures in English (back down, clamp down, tone down, etc). For translations, see the relevant verb entry (back, clamp, tone, etc).
You can always blame your kids when the cops batter down your door - although pleading ignorance is not a defence that will stand up in a court of law.