Sentence:  Considerable progress has been made on the discovery and mapping of many open system <WSD>pingos</WSD> in central Alaska and Yukon Territorynb..., as well as the discovery of <WSD>pingo</WSD>-like mounds in the shallow waters of the Beaufort Sea north of the mouth of the Mackenzie River. The greatest advance in <WSD>pingo</WSD> research in the last decade has been a consideration and understanding of theory and rate of <WSD>pingo</WSD> growth ... 
Meaning of the word marked with <WSD> tags:  A conical mound of earth with an ice core caused by permafrost uplift, particularly if lasting more than a year. (from 1920s)