1708, "pertaining to the Silures," from Latin Silures "ancient British tribe inhabiting southeast Wales." Geological sense is from 1835, coined by Sir Roderick Impey Murchison (1792-1871) because rocks of this period are especially frequent in Wales.
silly
silo
Siloam
silphium
silt
Silurian
silvan
silver
silver bullet
silver lining
silver screen
)window.location='https://www.paypal.com/cgi-bin/webscr?cmd=_donations&business=byronic106@yahoo.com&lc=US&item_name=Donation+to +Help+Keep+Etymonline+Free+and+Open&no_note=0&cn=&curency_code=USD&bn=PP-DonationsBF:btn_donateCC_LG.gif:NonHosted'){kind=link}