'Solemn' in the Bible

On the first day [of the feast] you shall have a holy and solemn assembly, and on the seventh day there shall be another holy and solemn assembly; no work of any kind shall be done on those days, except for the preparation of food which every person must eat—only that may be done by you.

Moses took the bones of Joseph with him, because Joseph had made the Israelites swear a solemn oath, saying, “God will certainly come to your aid; then you must take my bones with you from this place.”

And he said unto them, This is that which Jehovah hath spoken, Tomorrow is a solemn rest, a holy sabbath unto Jehovah: bake that which ye will bake, and boil that which ye will boil; and all that remaineth over lay up for you to be kept until the morning.

Six days shall work be done, but on the seventh day is a sabbath of solemn rest, holy to Jehovah: whosoever doeth any work on the sabbath day, he shall surely be put to death.

Six days shall work be done; but on the seventh day there shall be to you a holy day, a sabbath of solemn rest to Jehovah: whosoever doeth any work therein shall be put to death.