-al1 Also -ial, -orial, and -ual.
Forming adjectives and some nouns.
[Variously from French -el or -aille, or Latin -alis.]
This suffix can be added to many nouns to create associated adjectives. Several thousand examples exist, often as compound endings with other suffixes. Originally the ending was attached to words from Latin roots (annual, infernal), but was later extended to those from Greek (historical, comical), and sometimes native English sources (tidal). Other examples are accidental, eternal, gradual, individual, natural, paternal, universal, and visual.
Adjectives in -ial often derive from Latin words in -ialis, where the i is contributed by the stem: celestial, official, partial, special. Adjectives in -orial are related to or derived from Latin or English nouns which end in -or or -tor (see -or1): curatorial, dictatorial, janitorial, professorial, or from Latin words ending in -oralis, or English nouns in -ory1: categorial, purgatorial, territorial. Adjectives in -ual derive from Latin words in -ualis (annual, sensual, virtual) or -uus (continual, intellectual, perpetual).
Nouns in this ending contain the idea of action or process, usually based on French or Latin verbs, for example arrival, the act or action of arriving, and denial, the act of denying something. Other common examples are approval, dismissal, proposal, recital, rehearsal, survival, and trial.