The shankbone of a lamb is a traditional element of the Seder ritual. It belongs on the table as a symbol of the Passover sacrifices that Jews have not made since the year 70, when the Roman army destroyed the Temple in Jerusalem.
what does it mean
Lamb can be kosher for Passover. However, Ashkenazi Jews traditionally do not eat lamb during Passover.
The shank bone, typically displayed on the seder plate during Pesach or Passover, symbolized the sacrificial lamb. The blood from the lamb was supposedly used to paint the door and window frames of Jewish households to identify them to the angel of death when it slew the firstborn sons of the Egyptians, so that it would "pass over" those houses and spare the Jewish children.
The Seder meal uses either a lamb bone or a turkey/chicken neck to represent the Paschal (lamb) sacrifice. The Israelites offered a lamb as a sacrifice at the first Passover. They put the blood of this lamb on their doorways as a signal for the Angel of Death to "Pass-Over" their houses and not kill their firstborn sons. All the other firstborn sons of Egypt died in the tenth and final plague. Modern Passover meals can use a chicken or turkey neck in place of the lamb bone since the Holy Temple is unavailable and they therefore want to use something dissimilar to the sacrificial lamb, yet still use a bone to remind them of the sacrifice.
The first night of Passover is the Seder night. During the Seder-meal, there are a number of symbolic foods on the table. One of them is a roasted lamb or goat shank-bone, chicken wing, or chicken neck; symbolizing the korban Pesach (Passover sacrifice), which was a lamb that was offered in the Temple in Jerusalem, then roasted and eaten as part of the meal on Seder night.
It was to be a yearling male lamb or billy goat (Exodus 12). See also:More about Passover
The Passover Lamb
had gadya is not Hebrew. It is Aramaic for "one lamb" and is the name of a famous Passover song.
A lamb.
Hebrew phrase written in English letters. It simply means "Passover". You may see it spoken by Jews in reference to the "Passover Lamb" or "Paschal Lamb".
what if a child swallowed small lamb bone
The Torah (Exodus ch.12) specifies matzoh, bitter hers and the meat of the pesach-sacrifice. Other foods are not mentioned, but wine, vegetables and fruits were probably on the menu.