在英語合成詞中，有一種不是很普遍的，也較少人注意的，那就是疊聲合成詞(repetition compounds)。

疊聲合成詞多數是名詞，也可轉化為形容詞、動詞或副詞，有三種形式：

Ⅰ兩個字都相同，如：

● He pooh-poohed my idea.(輕視)

● It is a hush-hush report not to be made public.(秘密的)

● The boy said bye-bye to his parents.(再見)

其他類似的疊聲合成詞有：

clank-clank(鏈子聲), drip-drip(雨水聲), tap-tap(打字機的聲音), so so(馬馬虎虎), goody-goody(偽善的), fifty-fifty(各半的), pretty-pretty(打扮得很俗氣的), thump-thump(砰然聲), snip-snip(剪聲)等。

Ⅱ第二字的元音和第一字的不同，如：

● Electric networks criss-cross the whole island.(交叉往來)

● The government dilly-dallied over lengthening the retirement age.(猶疑不決)

● The blinds flip-flopped in the wind.(飄搖、搖曳)

● The drunkard zig-zagged along the road.(彎彎曲曲地走)

● Most women like knick-knacks.(小裝飾品)

● Is it possible to get rid of the riff-raff of a society?(下等人)

● The graduating students had a pleasant sing-song in the garden.(歌唱會)

● Do you like wishy-washy soup?(淡而無味的)

Ⅲ第二字的輔音和第一字的不同，如：

● Barbarians in ancient times had to kow-tow to government officials.(叩頭)

● Some people are not used to the hub-bub of the city. (喧囂)

● I pity those who lead a humdrum life year in year out.(單調的)

● Willy-nilly, young people at the age of 18 must go for military training.(不管愿意或不愿意)

● Don’t play hanky-panky with your friends.(陰謀詭計)

● When rain suddenly came, the pedestrians ran helter-skelter.(狼狽地)

● Tom and his friends used to hob-nob in the bar.(共飲、親切地交談)

● The defeated soldiers retreated pell-mell.(混亂地)

● The market in the morning is usually filled with hurly-burly.(喧鬧)

疊聲合成詞形象清新，但數量不多，用的范疇也較局限，通常都不在嚴肅或正式的場合出現。