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).
These phrases act like ballast that weigh down overly terse and functional statements, making them less angular and slim-lined and more pleasantly rounded and waffly.