A “blocked creature” is an attacking creature that has been blocked by a creature this combat, or has become blocked as the result of a spell or ability this combat. Unless the attacking creature leaves combat, it continues to be a blocked creature through the end of combat step, even if the creature or creatures that blocked it are no longer on the battlefield or have otherwise left combat by then.

Smite : règles, fonctionnement et interactions (MTG)

Smite is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Destroy target blocked creature.

How it works : Smite

Original English text — Wizards of the Coast / Scryfall

#1June 15, 2010· Wizards of the Coast
A “blocked creature” is an attacking creature that has been blocked by a creature this combat, or has become blocked as the result of a spell or ability this combat. Unless the attacking creature leaves combat, it continues to be a blocked creature through the end of combat step, even if the creature or creatures that blocked it are no longer on the battlefield or have otherwise left combat by then.
No other card is named in this ruling.

Interactions with other cards

These cards' text mentions Smite.

Smite the Deathless

Smite the Deathless deals 3 damage to target creature. That creature loses indestructible until end of turn. If that creature would die this turn, exile it instead.

Elspeth's Smite

Elspeth's Smite deals 3 damage to target attacking or blocking creature. If that creature would die this turn, exile it instead.

Cindercone Smite

Cindercone Smite deals 2 damage to target creature. Then create a Treasure token if you weren't the starting player.

Radiant Smite

Destroy target creature with power 4 or greater. If you weren't the starting player, you gain 4 life. Cycling {W} When you cycle Radiant Smite, if you weren't the starting player, you gain 2 life.