This glossary is meant as a pronunciation guide to the terms used in Wing Chun; it's not meant as a guide to proper spelling. Though these words are always pronounced the same, there's no "correct" way to write them in English--which has led to many variations in spelling.
The People's Republic of China has modernized and standardized how Chinese is written in English, but this system isn't in widespread use by Chinese outside mainland China. China's official dialect is Mandarin--the way the language is spoken in the Northern capital of Beijing. Many Southern Chinese speak a dialect known as Cantonese--the chief dialect of Hong Kong, and of Wing Chun.
Tones are everything in Cantonese. A word can have the meaning of "grandmother" or "horse", the only difference is in the tone! The seven tones of Cantonese, as outlined in Janey Chen's "A Practical English-Chinese Pronouncing Dictionary" (Rutland: Tuttle, 1970), are represented by:
á = high rising
â = high level
à = high falling
a = middle level
áH = low rising
aH = low level
àH = low falling
High level tone should have a straight line over the letter, but HTML doesn't include this mark so I've substituted a circumflex instead. The capital H doesn't change the sound, it only indicates the low level.
The only way to learn to pronounce these tones properly is by listening to and imitating someone who speaks Cantonese. Vowels are pronounced "a" as in father, "ai" as in high, "e" as in "send", "i" as in "sick", "o" as in "rock", "u" as in "sun."
Without the written characters even a native speaker will have difficulty deciphering many of these words by the way they're written in English. To see how they're written in Chinese, take a look at René Ritchie's Wingchunkuen Dictionary. Keep in mind too that Wing Chun terms are only descriptive words, that differ with each instructor. Individual words may also be found combined in various ways to make other compound phrases.