when one's life is hanging on a thread, relying on something like medicine to extend one's life; to be on the verge of just being able to survive with the help of something (such as money or medicine)
Definitions (粵典–words.hk)
動詞
身體虛弱到就嚟死咁濟，靠藥物、水、食糧等等嘅資源嚟維持生命 to struggle to sustain one's life with medication, water, food, etc.
佢成個禮拜冇食過嘢，淨係靠鹽水嚟吊命。
佢成个礼拜冇食过嘢，净系靠盐水嚟吊命。
keoi5 seng4 go3 lai5 baai3 mou5 sik6 gwo3 je5, zing6 hai6 kaau3 jim4 seoi2 lei4 diu3 meng6. He hasn't eaten anything for a week; his entire life depended on an IV drip.
我通咗兩晚頂，仲未趕好晒啲稿，而家靠咖啡嚟吊命。
我通咗两晚顶，仲未赶好晒啲稿，而家靠咖啡嚟吊命。
ngo5 tung1 zo2 loeng5 maan5 deng2, zung6 mei6 gon2 hou2 saai3 di1 gou2, ji4 gaa1 kaau3 gaa3 fe1 lei4 diu3 meng6. After pulling two all-nighters, I still haven't finished writing my articles. Coffee is now my only source of energy.
動詞
引申為經濟條件好差，有咗某啲嘢提供收入來源，先可以維持最基本嘅生活水平 (figurative) to survive on something providing a source of income and sustain a barely tolerable standard of living, especially when under poor economic conditions
佢冇埋份洗碗工之後，就一路都靠綜援吊命。
佢冇埋份洗碗工之后，就一路都靠综援吊命。
keoi5 mou5 maai4 fan6 sai2 wun2 gung1 zi1 hau6, zau6 jat1 lou6 dou1 kaau3 zung3 wun4 diu3 meng6. Since he lost his dishwasher job, he's been living on government allowance.