After 1-3 weeks of learning Thai, you will encounter the word ใจ (jai) over and over again. Even after you become advance you will continue to encounter it all the time, so why not learn it now?
jai words are used a lot for expressing feelings such as I am sad, he is narrow-minded, etc. You need to master jai words if you want to be able to express yourself freely.
When jai is a stand-alone word, it is sometimes translated to ‘heart’, sometimes translated to ‘mind’ depending on the context. For example, พูดในใจ (pôot nai jai) means to speak in one’s mind (to not say it out loud) and เธอจะอยู่ในใจฉันตลอดไป yòo nai jai chăn dtà-lòt bpai means you will be in my heart forever.
In the following word list jai will be attached with another word to form another completely different word. The words in this list are commonly used. Please take a look and study them to bring your Thai up a notch when it comes to expressing feelings.

- To understand
 เข้าใจ (Literally: to enter, mind)
 kâo jai
- To be interested
 สนใจ
 sŏn jai
- To be generous
 ใจกว้าง (literally: wide, mind)
 jai gwâang
- To impress/ be impressive 
 ประทับใจ (Literally: to imprint, mind)
 bprà-táp jai
- To be narrow-minded
 ใจแคบ (literally: mind, narrow)
 jai kâep
- To be impatient/Short-tempered
 ใจร้อน (literally: mind, hot)
 jai rón
- To be patient
 ใจเย็น (literally: mind, cool)
 jai yen
- To not easily give in
 ใจแข็ง (Literally: mind, strong)
 jai kăeng
- To easily give in
 ใจอ่อน (Literally: mind, weak)
 jai òn
- To be evil
 ใจดำ (Literally: mind, black)
 jai dam
- Mind wanders off
 ใจลอย (Literally: mind, float)
 jai loi
- To be nice
 ใจดี (Literally: mind, good)
 jai dee
- To be relieved
 เบาใจ (Literally: light, heart)
 bao jai
- To worry
 หนักใจ (Literally: heavy, mind)
 nàk jai
- To be care-free
 สบายใจ (Literally: comfortable, mind)
 sà-baai jai
- To cheat on somebody
 นอกใจ (Literally: outside, mind)
 nôk jai
- To be satisfied
 พอใจ (Literally: sufficient, mind)
 por jai
- To be shocked
 ตกใจ (Literally: to fall, mind)
 dtòk jai
- To be confident
 มั่นใจ (Literally: confident, mind)
 mân jai
- To be certain
 แน่ใจ (Literally: certain, mind)
 nâe jai
- To misunderstand each other
 ผิดใจ (Literally: wrong, mind)
 pìt jai
- To be sad/ To feel sorry
 เสียใจ (Literally: to go bad/rot, mind)
 sĭa jai
- To be extremely sad
 เศร้าใจ (Literally: sad, mind)
 sâo jai
- To try to make someone satisfy, happy
 เอาใจ (Literally: take, mind)
 ao jai
- To decide
 ตัดสินใจ (Literally: decide, mind)
 dtàt sĭn jai
- To be determined, work hard
 ตั้งใจ (Literally: set, mind)
 dtâng jai
- To let them get what they want
 ตามใจ (Literally: Follow, mind)
 dtaam jai
- To be hurt (emotionally)
 เจ็บใจ (Literally: Hurt, mind)
 jèp jai
- To heartache
 ปวดใจ (Literally: pain, mind)
 bpùat jai
- To change one’s mind
 เปลี่ยนใจ (Literally: To change, mind)
 bplìan jai
- To be surprised (with curiosity)
 แปลกใจ (Literally: to be strange, mind)
 bplàek jai
- To trust
 วางใจ (Literally: to place, mind)
 waang jai
- To be frighteningly shocked
 ใจหาย(หมดเลย) (Literally: disappear, mind)
 jai hăai
- To be passively angry
 น้อยใจ (Literally: little, mind)
 nói jai
- To be happy and satisfied
 อิ่มใจ (Literally: to be full, mind)
 ìm jai
- To sympathize, feel sorry for
 เห็นใจ (Literally: To see, mind)
 hĕn jai
- To get to know someone’s true nature
 ดูใจ (Literally: To look, mind)
 doo jai
- To be overly confident that you can get away with anything.
 ได้ใจ (Literally: can, mind)
 dâai jai
- To be brave
 ใจถึง (Literally: Mind, To reach)
 jai tĕung
- Center, Middle
 ใจกลาง (Literally: Mind, Center )
 jai glaang
- To be proud
 ภูมิใจ (Literally: Proud, mind )
 poom jai
- To be mean
 ใจร้าย (Literally: Mind, evil)
 jai ráai
I hope my explanation on ใจ (jai) words was useful to you. So don’t get confused when you see jai in so many words!
 
				