Students often ask me what is a good way to learn English vocabulary and it is a difficult question to answer. One suggestion I often make is to learn words in sets. For example for adjectives (形容詞) you can often learn an opposite (反対) word. In this way you can learn double the number of words and adjectives are always very useful for conversation.
Here are some common adjective pairs:
- big – small
- long – short
- clean – dirty
- hard – soft
- wet – dry
- fast – slow
You can sometimes also add the prefix (接頭辞) “un-” to adjectives to make an opposite, for example unintelligent (知力のない). Unintelligent is also softer than a more direct opposite word like stupid (ばかな).
On the other hand (他方では) you sometimes have to be a little careful when translating adjectives, as there are some differences between Japanese and English. For example the opposite pair of high and low in English is usually translated in Japanese as「高い」 and 「低い」. However, when we are talking about people’s height (背の高さ) , we translate 「背が高い」as tall and 「背が低い」as short.
Sometimes there are also cultural (文化的な) differences about what people think the best opposite for a word is. For example for Japanese people the opposite of 「甘い」is usually 「辛い」and so students sometimes think that in English the opposite of sweet is spicy. However in English we usually think the opposite for sweet is sour or bitter (but we might sometimes say salty too「塩辛い」）.