In other words / that is to say (换言之 / 也就是说)

Structure Statement。换言之 / 也就是说，paraphrase or logical consequence

换言之 (huàn yán zhī) and 也就是说 (yě jiùshì shuō) introduce a REFORMULATION: they restate what came before in other words, or draw out its logical consequence (他没有反对，换言之，他默许了). 换言之, literally 'changing the words', is the most cultivated and concise, at home in essays; 也就是说 ('that is to say') is neutral and works in careful speech too; 换句话说 ('to put it another way') sits between them. They serve to clarify, sharpen, or spell out the implication of what was said.

Examples

他tā没méi有yǒu反fǎn对duì，换huàn言yán之zhī，他tā已yǐ经jīng默mò许xǔ了le。
He didn't object; in other words, he had already tacitly assented.
需xū求qiú大dà于yú供gōng给jǐ，换huàn言yán之zhī，价jià格gé势shì必bì上shàng涨zhǎng。
Demand exceeds supply; in other words, the price is bound to rise.
他tā三sān天tiān没méi回huí消xiāo息xī，也yě就jiù是shì说shuō，这zhè件jiàn事shì已yǐ经jīng没méi戏xì了le。
He hasn't replied in three days; that is to say, this matter is already a lost cause.
投tóu票piào率lǜ不bù足zú半bàn数shù，换huàn言yán之zhī，结jié果guǒ缺quē乏fá足zú够gòu的de代dài表biǎo性xìng。
Turnout fell short of half; in other words, the result lacks sufficient representativeness.

Levels are indicative: they follow the standard Chinese Grammar Wiki (AllSet Learning) progression, not an official HSK 3.0 mapping. We never assign levels by eye.

This point and the other 370, with audio on every example, inside Wanyu.