Stocky means short and solidly built. Broad rather than tall, and not remotely thin.
It is a neutral or even complimentary word, which is worth knowing, since English has few polite ways to describe a heavy build. A stocky man suggests strength rather than weight, so it suits rugby forwards, farmers and boxers. Animals get it too, and a stocky pony is a sturdy one. Its opposites are lanky for tall and thin, and wiry for thin and strong.
1adjectivestockyShort and sturdily built.
“He was a stocky man with heavy shoulders.”
Middle English
stok
English
stock
English, today
stocky
Built from
From stock + -y. stock comes from Middle English stok. From Middle English stok, from Old English stocc, from Proto-West Germanic stokk, from Proto-Germanic stukkaz (“tree-trunk”). Modern senses are mostly referring either to the trunk from which the tree grows (figuratively, its origin and/or support/foundation), or to a piece of wood, stick, or rod. The senses of "supply" and "raw material" arose from a probable conflation with steck (“an item of goods, merchandise”) or the use of split tally sticks consisting of foil or counterfoil and stock to capture paid taxes, debts or exchanges. a doublet of chock.
Etymology from Wiktionary, CC BY-SA