Capable of being dismissed or ended; able to be rejected, removed, or discharged.
From dismiss plus the -ible suffix (variant of -able, from Latin -ibilis), meaning 'capable of being'; the -ible ending typically appears in formal or Latinate words.
Both 'dismissible' and 'dismissable' are correct, but courts and lawyers prefer 'dismissible' because it sounds more formal and Latinate—a small example of how professional jargon gravitates toward one spelling variant for prestige.
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