How would a go about making a program where the user enters a string, and the program generates a list of words beginning with that string?

Ex:
User: "abd"
Program:abdicate, abdomen, abduct...

Thanks!

Edit: I'm using python, but I assume that this is a fairly language-independent problem.

Use a trie.

Add your list of words to a trie. Each path from the root to a leaf is a valid word. A path from a root to an intermediate node represents a prefix, and the children of the intermediate node are valid completions for the prefix.