H6363 פֶּטֶר (peh'-ter)

KJV renderings: firstling, openeth, such as open.
Strong's definition: a fissure, i.e. (concretely) firstling (as opening the matrix)
Derivation: or פִּטְרָה; from H6362 (פָּטַר);

From James Strong's public-domain dictionaries (H), JSON edition by OpenScriptures (CC-BY-SA). Every dotted-underline word in the text links here.