Phono-semantic — one part hints at the meaning, another at the sound
Example phrases
他心底一直记得那位老师当年的鼓励。Tā xīndǐ yìzhí jìde nà wèi lǎoshī dāngnián de gǔlì.Deep in his heart, he has always remembered that teacher's encouragement from those years.
那句话一直藏在她心底,从来没有对别人说过。Nà jù huà yìzhí cáng zài tā xīndǐ, cónglái méiyǒu duì biérén shuō guo.Those words have always been hidden deep in her heart, and she has never told anyone.
听到朋友考上了大学,他打心底为她高兴。Tīngdào péngyou kǎo shàng le dàxué, tā dǎ xīndǐ wèi tā gāoxìng.Hearing that his friend got into university, he was truly happy for her from the bottom of his heart.