Here’s an English definition from the introductory paragraphs of “Soil-Vegetation Relationships in Hawaiian Kipukas” by D. Mueller-Dombois and Charles H. Lamoureux in Pacific Science 21(1967):286-299.
KIPUKA, the Hawaiian word for "opening," has come into scientific usage as a term used to designate an older area on the slopes of volcanic mountains that has been surrounded by more recent lava flows. Kipukas are common landscape features on the slopes of Mauna Loa and Kilauea volcanoes on the [Big Island] of Hawaii, where they can be readily recognized as islands of denser vegetation in the vast, sparsely vegetated areas. They range in size from a few square meters to hundreds of acres.The usual Hawaiian (and Hawaiian Pidgin) term for ‘hole’ in the sense of ‘perforation, gap, blank (in a form), zero’ (vs. lua ‘pit, hole in the ground, latrine’) is puka, as in one-puka-puka, the U.S. Army's 100th Infantry Battalion. Hawaiian kīpuka may be a puka with an intensifying prefix, and it has an interesting range of meanings that have nothing to do with lava. Here's the full entry from Pukui and Elbert's (1986) revised and enlarged edition of their Hawaiian Dictionary:
Kipukas are of special interest for several reasons. As vegetation islands they provide seedsource centers for the invasion of vegetation on new volcanic material. As vegetation islands they represent somewhat simplified ecosystems, analogous to bogs or lakes, that are very suitable for studying internal ecological relationships. The isolation of small populations in kipukas provides unique opportunities for evolutionary studies.
1. Variation or change of form (puka, hole), as a calm place in a high sea, deep place in a shoal, opening in a forest, openings in cloud formations, and especially a clear place or oasis within a lava bed where there may be vegetation. 2. Short shoulder cape; cloak, poncho. 3. Loop, lasso; snare, as for catching owls (a rat was tied to a sharp stick in a net; the owl, pouncing on the rat, was pierced by this stick).Ouch!
UPDATE: As its Hawaiian etymology suggests, the kipuka is usually a hollow spot in a lava flow. A kipuka that projects above the surrounding lava is a steptoe, “named after Steptoe Butte, a quartzite protrusion above the Columbia Plateau lava flows near Colfax, Washington” or a dagala, from an Italian term for “an islandlike mass of older land surrounded by later lava flows,” according to the (1960) second edition of the Glossary of geology and related sciences: A cooperative project of the American Geological Institute.