Grammar Glossary

A transitive verb must have a direct object for it to be used grammatically. For instance, "to punish" is a transitive verb because you can't say "He punishes" you have to say "He punishes the man" (or the dog, or something).

An instransitive verb doesn't take a direct object. For instance, "to sleep" is an instransivite verb because you can say "He sleeps" but not "He sleeps the man" (or the dog, or something).

A verb can be ambitransitive (both intransitive and transitive). For instance, "to read" is ambistransitive because you can say "He reads" and "He reads the book."

Here's my own dumbed-down version of how to remember the difference (Katee already gave the smart version). Transitive means the action is carried over from one thing to another thing. Intransitive means the action stays with one thing.

The most famous example is the lie/lay issue that has plagued writers since, well, they started writing.

Lie is intransitive. The action stays with one thing. The book lies on the table.

Lay is transitive. The action flows from one thing to another thing. I lay the book on the table. (See, the action went from me to the book.)

When I lay the book on the table, it lies there. Simple.