A prefix is an affix which is placed before the stem of a word. Adding it to the beginning of one word changes it into another word.
Prefix (tiền tố) là phần thêm phía trước của một từ có chức năng làm cho nghĩa của từ đó khác đi so với từ gốc.
Prefix Meaning Key Word
| anti- | against | antifreeze |
| de- | opposite | defrost |
| dis-* | not, opposite of | disagree |
| en-, em- | cause to | encode, embrace |
| fore- | before | forecast |
| in-, im- | in | infield |
| in-, im-, il-, ir-* | not | injustice, impossible |
| inter- | between | interact |
| mid- | middle | midway |
| mis- | wrongly | misfire |
| non- | not | nonsense |
| over- | over | overlook |
| pre- | before | prefix |
| re-* | again | return |
| semi- | half | semicircle |
| sub- | under | submarine |
| super- | above | superstar |
| trans- | across | transport |
| un-* | not | unfriendly |
| under- | under | undersea |
*Most frequent. The four most frequent prefixes account for 97 percent of prefixed words in printed school English.
