A bilingual dictionary is useful for looking up meanings of words, but it is not so for using (e.g. writing and speaking) words. Typically in a such dictionary, an entry provides the corresponding terms in another language and some examples. Usage explanations may be provided if the word or phrase is commonly used incorrectly. Still, the coverage is rather limited for everyday uses.
In a Chinese-English dictionary, the entry for 兩 might list "two". This seems adequate at the first glance. After all, how complicated can the word "two" be? However, while the word "two" is simple, how the concept of two is referred in English is quite complicated. Consider a few English language customs:
- In English, using "2" in a written sentence is normally considered poor style.
- "two" is omitted if the context is clear about it. For example, use "sisters" instead of "two sisters" if it is understood to refer to sisters Jenny and Tammy. (In contrast, in Chinese, the literal "two sisters" sometimes mean "two close sistors").
- For conciseness, "both" is sometimes used.
- Often, the concept is referred by prefixes lik "bi-" (e.g. "bidirectional").
- Depending on context, "couple", "pair", or even "twin" may be preferrable.
Similarly, in a English-Chinese dictionary, the entry for "two" may need to list and explain 二, 雙, 兩, and 對.
While few language learners and translators would bother looking up the word "two", its case illustrates an often overlooked reality: in translation, "simple" words are often the trouble makers. Thus, for adequate coverage, a dictionary may have to explain the usages for most words; yet, this is usually not possible because dictionaries are expected to be concise.