Usage of the character 改

to change one's tune
to modify one's previous remark
to change the way one addresses sb (as when one marries and starts to call one's husband's parents 爸爸 (bàba) and 媽媽／妈妈 (māma))

cuàngǎi

篡改

[篡改]

to tamper with
to falsify

gǎizhuāng

改装

[改裝]

to change one's costume
to repackage
to remodel
to refit
to modify
to convert

gǎidìng

改订

[改訂]

to revise (text, plan etc)

láogǎi

劳改

[勞改]

abbr. for 勞動改造／劳动改造 (láodònggǎizào)
reform through labor
laogai (prison camp)

gǎigǎo

改稿

[改稿]

to revise a manuscript

gǎiguān

改观

[改觀]

change of appearance
to revise one's point of view

gǎijiàn

改建

[改建]

to rebuild
to transform (a building)
to refurbish

gǎiqī

改期

[改期]

to reschedule
to rearrange (e.g. a meeting)
to postpone

gǎidào

改道

[改道]

to change route
to divert (a road or a watercourse)

gǎiqiān

改签

[改簽]

to change one's reservation
to transfer to a different flight, airline, bus or train

shāngǎi

删改

[刪改]

to edit
to modify
to alter (written material)

gǎiháng

改行

[改行]

to change profession

gǎixìn

改信

[改信]

to convert (to another religion)

gǎishuǐ

改水

[改水]

to improve water quality

zàigǎi

再改

[再改]

to renew
to reform

mógǎi

魔改

[魔改]

(slang) to modify in a fantastical way; to modify heavily

gǎidòng

改动

[改動]

to alter
to modify
to revise

jīgǎi

基改

[基改]

genetic modification (GM)
abbr. for 基因改造 (jīyīngǎizào)

cuàngǎi

窜改

[竄改]

to alter
to modify
to change
to tamper

gǎizuǐ

改嘴

[改嘴]

to deny
to go back on one's word

gǎihuàn

改换

[改換]

to change (sth)
to alter (sth)
to change over (to sth else)

gǎipàn

改判

[改判]

(law) to amend a judgment; to commute
(in a contest or exam) to change the original decision or score

gǎijìn

改进

[改進]

to improve; to make better
improvement
CL:個／个 (gè)

gǎizhì

改制

[改制]

to reorganize
to restructure

gǎizhuī

改锥

[改錐]

screwdriver
CL:把 (bǎ)

gǎimíng

改名

[改名]

to change one's name

hùngǎi

混改

[混改]

mixed ownership reform (abbr. for 混合所有制改革 (hùnhésuǒyǒuzhìgǎigé))

gǎixué

改学

[改學]

to switch from one major or faculty to another (at a university)

gǎibiàn

改变

[改變]

to change
to alter
to transform

gǎiyuán

改元

[改元]

to change an emperor's or ruler's reign title (old)

gǎigé

改革

[改革]

reform
CL:次 (cì),種／种 (zhǒng),項／项 (xiàng)
to reform

tǔgǎi

土改

[土改]

land reform (abbr. for 土地改革 (tudǐgǎigě))

gǎibiān

改编

[改編]

to adapt
to rearrange
to revise

gǎishàn

改善

[改善]

to make better; to improve
CL:個／个 (gè)

shěngǎi

审改

[審改]

to check and revise

túgǎi

涂改

[塗改]

to alter (text)
to change by painting over
to correct (with correction fluid)

gǎibǎn

改版

[改版]

to revise the current edition
revised edition

gǎiguò

改过

[改過]

to correct one's errors; to mend one's ways

jīngǎi

金改

[金改]

financial reform (abbr. for 金融改革 (jīnrónggǎigé))

huǐgǎi

悔改

[悔改]

to repent
repentance

gǎiyàng

改样

[改樣]

to change completely

xiūgǎi

修改

[修改]

to amend
to alter
to modify

xiūgǎigǎo

修改稿

[修改稿]

revised draft
new version (of a document)

gǎigézhě

改革者

[改革者]

reformer

gǎikǒufèi

改口费

[改口費]

a gift of money given by parents on both sides after a wedding, to their new daughter-in-law or son-in-law

Mòdǐgǎi

末底改

[末底改]

Mordechai (name)

túgǎiyè

涂改液

[塗改液]

correction fluid

xiǎogǎigǎi

小改改

[小改改]

(Internet slang) young lady (Cantonese-influenced alternative to 小姐姐 (xiǎojiějie))

dòupīgǎi

斗批改

[鬥批改]

struggle, criticize, and transform (Cultural Revolution catchcry)

gǎigéjiā

改革家

[改革家]

reformer

gǎigépài

改革派

[改革派]

the reformist party

Fāgǎiwěi

发改委

[發改委]

abbr. for 國家發展和改革委員會／国家发展和改革委员会, PRC National Development and Reform Commission (NDRC), formed in 2003

láogǎiyíng

劳改营

[勞改營]

correctional labor camp

Gǎizéxiàn

改则县

[改則縣]

Gerze county in Ngari prefecture, Tibet, Tibetan: Sger rtse rdzong

jīyīngǎizào

基因改造

[基因改造]

genetic modification (GM)

gǎi'èxiàngshàn

改恶向善

[改惡向善]

turn away from evil and follow virtue

zhāowénxīgǎi

朝闻夕改

[朝聞夕改]

lit. heard in the morning and changed by the evening
to correct an error very quickly (idiom)

gǎicháohuàndài

改朝换代

[改朝換代]

to transition to a new dynasty or regime

zhāolìngxīgǎi

朝令夕改

[朝令夕改]

to make frequent or unpredictable changes in policy (idiom)

gǎiliángzhǔyì

改良主义

[改良主義]

reformism (i.e. favoring gradual change as opposed to revolution)

tǔdìgǎigé

土地改革

[土地改革]

land reform

fānrángǎitú

幡然改图

[幡然改圖]

to change one's plan all of a sudden (idiom)

gǎiguòzìxīn

改过自新

[改過自新]

to reform and start afresh (idiom); to turn over a new leaf

gǎitóuhuànmiàn

改头换面

[改頭換面]

to change outwardly while remaining essentially the same (derog.) (idiom)
(Tw) (non-derogatory) to change considerably
to undergo a transformation

gǎigékāifàng

改革开放

[改革開放]

to reform and open to the outside world
refers to Deng Xiaoping's policies from around 1980

yóumíngǎizào

游民改造

[遊民改造]

rehabilitation of displaced persons

zhāoguòxīgǎi

朝过夕改

[朝過夕改]

to correct in the evening a fault of the morning (idiom)
to quickly amend one's ways

gǎixiányìzhé

改弦易辙

[改弦易轍]

change of string, move out of rut (idiom); dramatic change of direction
to dance to a different tune

zhīguògǎiguò

知过改过

[知過改過]

to acknowledge one's faults and correct them (idiom)

tònggǎiqiánfēi

痛改前非

[痛改前非]

completely correcting one's former misdeeds (idiom); to repent past mistakes and turn over a new leaf
a reformed character

yīgǎigùzhé

一改故辙

[一改故轍]

complete change from the old rut (idiom); dramatic change of direction
a volte-face
to change old practices

miànbùgǎisè

面不改色

[面不改色]

(idiom) not bat an eyelid

zhèngzhìgǎigé

政治改革

[政治改革]

political reform

gǎigéjìnchéng

改革进程

[改革進程]

reform process

jīnrónggǎigé

金融改革

[金融改革]

financial reform

gǎihuànméntíng

改换门庭

[改換門庭]

to improve one's family's social status by moving up in the world
to switch one's allegiance to a new patron

sǐbùgǎihuǐ

死不改悔

[死不改悔]

not to repent even facing death (idiom)
unrepentant
very obstinate

lüjiàobùgǎi

屡教不改

[屢教不改]

lit. not to change, despite repeated admonition
incorrigible
unrepentant

jīyīnxiūgǎi

基因修改

[基因修改]

genetic modification

láodònggǎizào

劳动改造

[勞動改造]

reeducation through labor
laogai (prison camp)

jīngjìgǎigé

经济改革

[經濟改革]

economic reform

Zōngjiào Gǎigé

宗教改革

[宗教改革]

(Protestant) Reformation

gǎihuànménlü

改换门闾

[改換門閭]

see 改換門庭／改换门庭 (gǎihuànméntíng)

zhīcuònénggǎi

知错能改

[知錯能改]

to recognize one's mistakes and be able to reform oneself (idiom)

wénzìgǎigé

文字改革

[文字改革]

reform of the writing system

gǎishàntōngxùn

改善通讯

[改善通訊]

to improve communications

gǎixiéguīzhèng

改邪归正

[改邪歸正]

to mend one's ways (idiom)
to turn over a new leaf

gǎishànguānxi

改善关系

[改善關係]

to improve relations

jīxínángǎi

积习难改

[積習難改]

old habits are hard to change (idiom)

gǎibiànxíngxiàng

改变形像

[改變形像]

transfiguration

gǒugǎibùliǎochīshǐ

狗改不了吃屎

[狗改不了吃屎]

lit. a dog can't stop himself from eating shit (idiom)
fig. bad habits are hard to change

Gǎidìng Yīlí Tiáoyuē

改订伊犁条约

[改訂伊犁條約]

Treaty of Saint Petersburg of 1881 in which Russia agreed to hand back Yili province to Qing China in exchange for compensation payment and unequal treaty rights

Zhōng E Gǎidìng Tiáoyuē

中俄改订条约

[中俄改訂條約]

Treaty of Saint Petersburg of 1881, whereby Russia handed back Yili province to Qing China in exchange for compensation payment and unequal treaty rights

Guójiā Fāzhǎn Gǎigé Wěi

国家发展改革委

[國家發展改革委]