A FREE English Dictionary Database from

You can check the meaning of one word, or a whole page.

Enter your query in the search box, or choose a letter from the menu below.

Try our SpellChecker here, or our English Thesaurus here.

 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
 Exact Word  Within Words  Within Descriptions
Piston (n.) A sliding piece which either is moved by, or moves against, fluid pressure. It usually consists of a short cylinder fitting within a cylindrical vessel along which it moves, back and forth. It is used in steam engines to receive motion from the steam, and in pumps to transmit motion to a fluid; also for other purposes.