What does Shiloh mean?
Etymology unsettled. Most often read 'tranquil, peaceful, place of rest,' linked to the sanctuary town Shiloh and a root sh-l-h. The cryptic term in Genesis 49:10 is alternatively read shelo, 'he whose it is' (taken messianically). The popular gloss 'his gift' is not well supported. Hedge as disputed; used for both sexes in modern practice.
What does Leviathan mean?
Hebrew livyathan, a great sea-serpent/monster, generally glossed 'twisted, coiled' and derived (per Gesenius) from the root l-w-h 'to twine, wind' with a suffix, i.e. 'wreathed one'. Flag: the derivation is disputed (some hold it a loanword), and in use it is the name of a biblical serpent-monster; the 'coiled serpent' sense is the established reading.