This is the 4352nd most frequent Japanese word.
半島
Peninsula.
半島 is used here to refer to geographical features extending into water, emphasizing its nature as a landform.
日本には本州以外にいくつかの小さな半島があります。
Japan has several small peninsulas besides Honshu.
半島 in this sentence signifies a specific peninsula, highlighting it as a location of interest.
その半島には多くの古代遺跡が見つかっています。
Many ancient ruins have been found on that peninsula.
半島 is used as an adjective describing a region characterized as being part of or belonging to a peninsula.