/'hɑ:dn; `hɑrdn/
v
1 (a) [I, Tn] (cause sth to) become hard, strong, unyielding, etc （使某事物）变硬、变坚强、变坚定等
*The varnish takes a few minutes to harden. 清漆几分钟就能变硬.
* Attitudes to the strike have hardened on both sides. 双方对罢工所持的态度更加强硬了.
* For her own good, you must harden your heart, ie not allow yourself to show love, pity, etc. 替她着想, 你不能心软（不要流露自己的爱、同情等）.
(b) [esp passive 尤用于被动语态
*Tn, Tn.pr] ~ sb (to sth) make sb less sensitive (to sth) 使某人（对某事）麻木不仁或毫不在乎
*a hardened criminal, ie one who shows no sign of shame or repentance 怙恶不悛的罪犯
* He became hardened to the suffering around him. 他对周围的苦难现象已经见怪不怪了.
2 (phr v) harden (sth) off (cause young plants, esp seedlings to) become strong enough for planting outside （使幼小植物, 尤指幼苗）增强耐受能力以备露天种植.

v [I and T]
to become firm or stiff, or to make something firm or stiff
≠ soften
　It will take about 24 hours for the glue to harden.
if your attitude hardens, or if something hardens it, you become more strict and determined and less sympathetic
≠ soften
　Attitudes towards the terrorists have hardened even more since the attack.
written if your face or voice hardens, or if something hardens it, you look or sound less sympathetic or happy
≠ soften
　His face hardened momentarily, then he looked away.
harden your heart
to make yourself not feel pity or sympathy for someone