The use of the title 'Trẫm', carrying a special significance, is the best choice for the unique existence of Emperor Qin Shi Huang.
Those who enjoy watching Chinese historical dramas are surely familiar with terms of address like 'Your Excellency', 'My Lord', 'Esteemed One'... These terms may sound polite, but in ancient Chinese royal courts, they were everyday language, accessible to all.
In feudal dynasties, the title reserved solely for the Emperor was 'Trẫm', a distinctive address originating from the era of Qin Shi Huang, one of China's earliest emperors.

In 221 BCE, Qin Shi Huang unified six feudal states, establishing the first centralized dynasty in Chinese history - the Qin Dynasty.
Ascending to the throne at the age of 13, Qin Shi Huang became Emperor at 38. Instead of adopting traditional royal titles like previous monarchs of the Shang and Zhou dynasties, Qin Shi Huang, to signify the unification of China and the greatness of the Qin Dynasty, innovated a new title - 'Emperor' - and referred to himself as Emperor Shi Huang.
In this era, akin to a new dawn of Chinese civilization, Qin Shi Huang decided to undertake a major reform and implement a new system of governance, including establishing a centralized administrative system appointed by the court instead of granting fiefs to nobles as before, allowing peasants to own land. The populace had to learn a standardized script, use uniform measurement methods, and abide by a rigorous legal system.
Qin Shi Huang, who believed he had successfully surpassed the 'Three Sovereigns and Five Emperors' (ancient rulers believed to have laid the foundation of Chinese civilization), also chose for himself a unique self-reference, 'Trẫm'.

'Trẫm' (朕) first appeared in the era when ancient Chinese used Oracle Bone Script (inscriptions carved on animal bones). However, at this stage, 'Trẫm' was a commonly used self-reference that everyone could employ. Nonetheless, compared to other forms of address, 'Trẫm' was often favored by the powerful and influential. By the end of the Warring States period, 'Trẫm' gradually fell out of everyday speech, replaced by 'Ngã' and 'Ngộ' (both meaning 'I, myself').
Therefore, Qin Shi Huang chose 'Trẫm' - a term that was no longer common among ordinary people, symbolizing his uniqueness while facilitating quicker adaptation among the populace and avoiding the autocratic self-reference of emperors.
Furthermore, Qin Shi Huang's use of 'Trẫm' as a self-reference holds deeper significance. Based on pictographic characters (one of the six creative ways of writing Chinese characters, including Pictograms, Ideograms, Phonetics, Compound Ideographs, Loan Characters, Derivative Characters), the original form of 'Trẫm' resembled a composition consisting of the character 舟 ('boat') on the left and the character 灷 on the right, forming the meaning of 'fire in a boat'.

In ancient times, human society's labor productivity was low and mostly relied on the natural environment. During that time, people often settled along the banks of rivers, where river water could be used for drinking and washing, and fish from the river was also a major food source. In such circumstances, boats became an essential tool for survival and fishing.
Fire also held a significant position in ancient civilizations; humans used fire for cooking food and dispelling darkness. Wild animals have an innate fear of fire, thus humans could avoid being harmed by predators. Moreover, with fire, humans could innovate and create many new things.

Since ancient times, humans have revered fire, giving rise to supreme beings like the 'God of Fire'. Alongside this, fire has been regarded as a symbol of status.
It can be said that boats and fire, one representing wealth and prosperity, the other symbolizing power, when combined, represent the ultimate authority according to ancient beliefs.
From this perspective, the term 'Trẫm', carrying the symbolism of boats and fire, truly becomes the best choice for the unique existence of Emperor Qin Shi Huang. Since then, emperors in subsequent Chinese dynasties have also used this self-reference, becoming a familiar form of address as we have seen in historical dramas.
Source: Sohu