| A | B |
| subconscious | not fully aware; occurring below your level of thinking and awareness |
| subcutaneous | under the skin |
| subdue | to bring under control |
| subfreezing | below the freezing point |
| subirrigate | to water something from under the ground |
| subject | to put under someone else's control |
| submarine | a watercraft that stays under water |
| submerge | to put under water |
| subordinate | a person who is under someone else in rank or importance |
| subway | a passageway under the ground; an electric underground railway |
| superb | splendid; excellent; beyond the expected |
| superimpose | to lay or place something over something else |
| superintendent | a person with the highest power, power above everyone else's |
| superior | above average in quality; excellent |
| supervisor | a person who stands over or above someone in rank; a manager in charge of someone else |
| surcharge | an amount of money (charge) over and above what is already being paid |
| surplus | a quantity or amount over and above what is actually needed; extra |
| surprise | something that is beyond what is expected |
| surreal | beyond what is real or believable; bizarre |
| surtax | an extra tax beyond the normal tax |