The verb bind makes bound in the past tense and as a past participle. So, for example, if you tied together two things this morning, you bound them together, and the two things were then bound together. Bounded is the past tense and past participle of the verb bound, which has two main definitions: (1) to confine or serve as the boundary of, and (2) to leap or spring. For example, an island is bounded on all sides by water, and somewhere a rabbit bounded out of a bush this morning.
Bind is one of a handful of -ind verbs whose -ound past tenses developed around the 16th century from earlier -and forms derived from Old English. Find and wind developed similarly; their old past-tense forms, fand and wand, gave way to found and wound in the 1500s. This bound is etymologically unrelated to the present-tense verb bound, which is newer to English. It entered English centuries after bind—its two main senses came from separate French sources in the early modern era—and it was inflected bounded right from the start.
Nothing interests us which is stark or bounded, but only what streams with life, what is in act or endeavor to reach somewhat beyond. [“Beauty,” Ralph Waldo Emerson (1860)]
In the van of the crowd were three men in scanty clothing; each had his hands bound together by a cord. [Romola, George Eliot (1863)]
The merchandise is first placed in an inside container, which is then bound with wire. [Popular Mechanics (1916)]
Jack bounded out from the tribe and began screaming wildly. [Lord of the Flies, William Golding (1959)]
The Third Ward, bounded by Huron Parkway, Glacier Way, and US is a Republican stronghold with few student residents.[Michigan Daily (1980)]
Turkey Waits and Wonders: How Closely Bound to Islam Is Election Victor? [New York Times (2002)]