Ascared, sometimes spelled a-scared, is an American colloquialism formed by fusing the synonyms scared and afraid. The word appears more often in speech than in writing.
In writing, it’s sometimes used with a mocking tone, often implying that the ascared person’s fear is childish—for example:
So, then the Arab League got ascared that Qaddafi would retaliate against them. [comment on Wall Street Journal]
It also appears in written dialogue in fictional works—for example:
An’ somehow you’re glad you’re goin’, an’ you ain’t a-scared to die … ["The Little Old Log Cabin," Robert W. Service]
Although ascared may be useful in written dialogue, it would be considered out of place formal or serious writing.