...when it comes to something with as long a history as tea, quite a lot.
Maybe you've noticed that in explaining facts about tea we refer to it as "tea," "tea plants," or "Camellia sinensis." The first two of these are common names, the last is the tea plant's scientific name.
Common names are what people ordinarily call plants on a daily basis. Examples of these for trees include sugar maple, blue spruce, or river birch. While scientific names are Latin and follow naming rules, common names have a lot more flexibility. It's not unusual for them to be regional in their use, so they often vary from place to place.
Because tea has been consumed as a beverage for over 4,700 years and used medicinally even longer than that, it's understandably difficult to say with accuracy what tea was called during its earliest use. Here's what we do know.
Research indicates that words used for tea prior to AD 725 weren't specific to tea. Instead the terms for it had multiple definitions, so a meaning could only be derived from context. Since tea wasn't known outside of China at this time, the following are all Chinese names.
T'u was one such word for tea in use from about 50 BC into the sixth century, but in addition to tea t'u could also refer to other plants such as bitter cabbage, grass, or rush.
Kia was another word for tea. It appeared in documents from the late third century that described it as an evergreen plant from whose leaves a beverage is made. Other definitions also existed for kia that had nothing to do with tea.
Ming was yet another early word for tea in use from about 500 BC through AD 800. Its earliest reference goes back to the time when tea was considered a vegetable. Research shows that Ming was described later as being a beverage, having medicinal uses, and being noted for its fragrance.
In AD 780 Lu Yu, a highly regarded Chinese poet, wrote a comprehensive book about tea called Ch'a Ching. In it he listed five Chinese words that referred to tea at the time. These included ch'a, kia, she, ming, and ch'uen.
The ambiguity problem came to an end with the introduction of the word ch'a for tea around AD 725. This was a period when tea was becoming increasingly popular. Tea, as we know it, has been its only meaning. Symbolically, it is created by eliminating one of the strokes from the Chinese character for t'u. The Cantonese word for the resulting character is ch'a (pronounced "chah") while t'e (pronounced "tay") is the word in the Amoy dialect spoken in the Fukien province.
The dispersal and subsequent adoption of these words around the world is fascinating in the most logical of ways. As tea was traded with people outside of China, the names that new tea-drinking cultures adopted for it hinged on whether it was obtained from the Cantonese or those speaking the Amoy dialect.
For example, some of the earliest tea trade took place between the Chinese and Arabs, Turks, and Russians over land routes. Because the Cantonese dominated these passages, ch'a was adopted in the new lands and evolved to become the common names of shai, chay, and chai, respectively. The Japanese and Persians also obtained their first tea from Cantonese merchants, and now both refer to the beverage as cha. The Portuguese are the only western Europeans who use a derivation of ch'a, calling it cha. As leading seafarers in the early sixteenth century, they dealt directly with tea merchants in Canton, so their linguistic decision makes perfect sense.
Of those using a derivation of t'e for its common name, the Dutch are the major influence. They began trading for tea not long after the Portuguese, but they acquired it in Java from Chinese merchants who spoke the Amoy dialect. Consequently, the Dutch word for tea became thee. As they sold their tea throughout Europe, they also spread its name. As a result, all of western Europe except Portugal uses some derivation of t'e. Other peoples also adopted a version of t'e including Korea, Scandinavian nations, and several eastern European countries.
The English spelling comes directly from the Dutch since they first supplied the beverage to them. In its earliest use in the 1650s, tea was spelled tee but pronounced "tay." By 1660 the spelling had become tea, but it continued to be pronounced "tay" well into the eighteenth century.
While it's somehow amazing that tea has only been known to the English-speaking world for such a short period (400 years) of its 4,700 year history, it's also appropriate that the world's most popular beverage (besides water) is called by such a diverse array of common names. So take your pick. Regardless of your choice you're sure to enjoy a hot cup of cha, teh, shai, t'e, tsa, chi, tey, cia, thee, chai, thay, teja, chay, etc.