名詞 lather:

1. the froth produced by soaps or detergents
   同義詞：soapsuds, suds
2. agitation resulting from active worry
   同義詞：fret, stew, sweat, swither
3. a workman who puts up laths
4. the foam resulting from excessive sweating (as on a horse)

動詞 lather:

1. cover with soap
2. beat severely with a whip or rod
   同義詞：flog, welt, whip, lash, slash, strap, trounce
3. form a lather
4. rub soap all over, usually with the purpose of cleaning
   同義詞：soap

1. He put some lather on his chin, and then began to shave.
   他在下巴上涂了些肥皂泡沫，然后開始刮臉。
2. Soap will not lather in sea-water.
   肥皂在海水里不起泡沫。

lath.er

n.（名詞）
A foam formed by soap or detergent agitated in water, as in washing or shaving.
肥皂泡：在水里攪動肥皂或清潔劑而形成的泡沫，如在洗衣服或剃須過程中
Froth formed by profuse sweating, as on a horse.
汗沫：如馬身上流出大量的汗而形成的泡沫
Informal A condition of anxious or heated discomposure; agitation:
【非正式用語】 焦躁：焦急或強(qiáng)烈不安的狀況；激動：
例句：
The students were in a lather over the proposed restrictions.
學(xué)生們因計劃實行的限制而感到不安

v.（動詞）
lath.ered,lath.er.ing,lath.ers
v.tr.（及物動詞）
To spread with or as if with lather.
以泡沫覆蓋：通過或好象是通過肥皂泡來擴(kuò)散
Informal To give a beating to; whip.
【非正式用語】 給（某人）一頓打；鞭打
v.intr.（不及物動詞）
To produce lather; foam.
產(chǎn)生肥皂沫；冒泡
To become coated with lather.
變得涂滿肥皂沫

來源：
Probably from Middle English latheren [to wash or soak clothes]
可能源自 中古英語 latheren [洗或浸泡衣服]
from Old English lôthran [to cover with lather] * see leu(…)-
源自 古英語 lôthran [用肥皂泡覆蓋] *參見 leu(…)-

【引伸】
lath.erer
n.（名詞）
lath.ery
adj.（形容詞）