i-adjective
Emphatic form of 長細い (ながほそい), with a geminated っ adding a colloquial, slightly rough or emphatic feel. Used for objects that are noticeably long and thin.
See also: 長細い (ながほそい)
このパンは長っぽそくて食べやすい。
This bread is long and thin, so it's easy to eat.
彼の
His fingers are long and slender.