a (geometry) Of a triangle, having all three interior angles measuring less than 90 degrees.
a (botany|of leaves) With the sides meeting directly to form a pointed acute angle at the apex, base, or both.
a (medicine) Of an abnormal condition of recent or sudden onset, in contrast to delayed onset; this sense does not imply severity (unlike the common usage).
a (medicine) Of a short-lived condition, in contrast to a chronic condition; this sense also does not imply severity.
a (context|orthography|after a letter) Having an acute accent.