ial

special, especial, crucial, infomercial, credential, initial, cordial, perennial, denial, material, tutorial, trial

suffix -ial (having characteristic of, pertaining to):
financial, facial, racial, artificial, commercial, beneficial, official, provincial, judicial, prejudicial, social, substantial, spatial, partial, impartial, essential, confidential, influential, potential, sequential, residential, controversial, ceremonial, testimonial, imperial, managerial, editorial, territorial, memorial, serial, editorial, conspiratorial, industrial, trivial, remedial