Botanically pineapple fruit is

Botanically pineapple fruit is Sorosis.
Sorosis is a fleshy fruit formed by the consolidation of many flowers with their receptacles, ovaries, etc, as the breadfruit, mulberry and pineapple.
The individual fruits of the flowers join together to create multiple fruits. After the first fruit is produced, side shoots are produced in the leaf axils of the main stem.
The ovaries develop into berries, which coalesce into large, compact, multiple fruits. The fruit of a pineapple is usually arranged in two interlocking helices.