Usage notes
Ordinarily, English does not allow the same letter to occur three times in a row. Accordingly, this term is usually written with a hyphen, as skull-like; at other times, one 'l' is dropped (resulting in skullike). As may be seen in the above quotations, however, some authors do write the term with the <lll> intact, and the Oxford English Dictionary does contain instances of other triple-letter words, including goddessship, frillless, and the county Rossshire. Other attested words which contain the same letter three times in a row include headmistressship and hostessship.
Origin
skull + -like
