A lot of people struggle to grow their vocabulary in their target language, especially when learning a language from a different language family, where there are less words that sound familiar.
The usual advice focuses on two things:
- Mnemonics, i.e. thinking of words in your target language that together sound somewhat similar to the target-language word, even if the meaning is completely different, and then inventing an absurd story that explains the link.
- Spaced repetition systems (SRS) like Anki, which weaponize the forgetting curve in order to ensure that you review words at exactly the right time so they are gradually transferred into your long-term memory - and so that you economize on the time you otherwise would have spent reviewing words you already know well.
These two tips are very important, but there is something even more important: an understanding that there is a near-universal system that underlies the vocabulary of human languages. You will discover this system in German and Chinese, in Hebrew, Russian and Indonesian, in Greek and Swahili, and I'm sure in most other languages. Why am I so confident? Because humans are lazy.
We are too lazy to invent completely new word roots for each new concept. For example we're too lazy to invent new words for "uninventive" and "unhelpful" rather than basing them off the words "inventive" and "helpful". To invent new words for "slowness" and "wetness" rather than basing them off the words "slow" and "wet". To invent new words for "widen", "broaden", "redden", "whiten" etc. which are completely distinct from "wide", "broad", "red", "white", etc. We just modify the existing word roots. In some cases we do have distinct words (e.g. "increase" instead of "biggen", "dry" instead of "unwet", "beauty" in addition to "prettiness"), but it is impractical to always invent distinct words and then to teach every native speaker of our language what all of these words mean. So instead, we use standard patterns. These patterns are a great tool for non-native speakers as well, and all too few are using it.
How to Use the System
First, you should become aware of the most common categories that humans naturally think in. This includes:
- Opposites. important-unimportant, helpful-unhelpful, healthy-unhealthy and so on. It appears to be natural for humans to think in terms of opposites. In English, this is mostly limited to adjectives, while in Swahili it's most common in verbs (e.g. funga to close, fungUa to open) and it's also possible to imagine in nouns (e.g. Esperanto lumo light, MALlumo darkness).
- People. buy-buyer, paint-painter, brew-brewer and so on. Typically something is added to a verb in order to get the noun for a person who does this action. Some languages (e.g. Esperanto, Chinese) have different suffixes depending on whether the person does this professionally, as a hobby or just right that moment. In English -ist is used only for professionals like pianists while -er (and sometimes -or) is used for any kind of person, professional or not.
- Places. brew-brewery, bake-bakery, owl-owlery and so on. Add the suffix -ery in order to name the place where the action takes place. Note that neither this suffix nor any other is 100% regular and universal - e.g. drinkeries are better known as bars. There will always be opposites, people, places etc. that don't follow the pattern, but learning the pattern is still supremely useful.
- Abstract concepts. sick-sickness, slow-slowness, wet-wetness and so on. Whenever you have an adjective, you probably have need to talk about this quality in the abstract.
- Ability. drink-drinkable, imagine-imaginable, believe-believable (or credible, derived from the Latin equivalent) and so on.
- Adverbs. slow-slowly, grateful-gratefully, quick-quickly and so on. This is probably the best-known suffix.
- Actions. wide-widen, broad-broaden, white-whiten and so on. Doing something that results in the state described by the adjective. This is relatively limited in English, but in other languages you might see the equivalent of healthy-en for to heal and many more.
- New adjectives. luck-lucky, sun-sunny, health-healthy and so on. Many adjectives are based on the noun with an added -y, and when there isn't a suitable adjective, people sometimes even create one, e.g. "And she said to me with that teacher-y voice..."
- Weaker forms. blue-bluish, pale-paleish, healthy-healthy-ish and so on. Weaker forms are mainly needed for adjectives, for added accuracy. However, many languages also have weaker forms for nouns, e.g. dog-doggie, kid-kiddie.
- Stronger forms. The opposite of the above. This doesn't appear to exist in English, but it does e.g. in Chinese (dà big - dàdà huge; gāoxìng happy - gāogāoxìngxìng overjoyed) and in Greek (mats match - matsara big match; gata cat - gatara huge cat).
Simply being aware that these are typical patterns in vocabulary can be a huge help in your studies. For example, I was confused when I found that the Arabic word maktab (derived from the root kataba to write) means both desk and office. There's a huge difference between a desk and an office, right? However, once I thought of it as writing-place, it immediately made sense. Similarly, when I was studying Swahili and I saw that to open and to close were essentially the same word (with extra -u-), I found that very confusing until I realised that the addition of -u- usually turns a Swahili word into its opposite, so they were saying something like to unclose for to open.
How to Go Further
If you want to be ahead of the game, have a teacher help you to figure out how each of the above categories work in your target language. This may be difficult to do for your teacher because many native speakers are not actively aware of the patterns. If so, try giving them a bunch of example words to translate, or use a dictionary and see if you can spot the patterns yourself. Don't expect all the words to follow the pattern - languages are not regular.
The only language that is extremely regular in the use of these patterns is Esperanto. That's how I became aware of these patterns (and a few others) in the first place. In Esperanto, you can pile any suffixes onto any word and as long as it's understandable, it's correct. There is no "we don't say it this way" in Esperanto if you call a dentist a toother, if you speak of relax-eries or say someone has unhelped you. In Esperanto, there are no limits to your imagination. The other place where such imagination is acceptable is in poetry. Poets are valued for understanding the above patterns of how our language forms new words and using them in order to create neologisms.
As a language learner with a limited vocabulary, learn these patterns and try to apply them to all words in order to rapidly increase your vocabulary. A lot of times you'll guess right. And even if you guess wrong and wind up saying eatable instead of edible or beautifulness instead of beauty, people will understand you and will help you learn the correct word.