Past is similar to Historic. Historic is a synonym of Significant. Significant is similar to Considerable. 
Stumble is related to Like. Like is related to Steam. Steam is related to River. River is related to Wet. 
Past <--SimilarTo--> Historic <--Synonym--> Significant <--SimilarTo--> Considerable 
Stumble <--RelatedTo--> Like <--RelatedTo--> Steam <--RelatedTo--> River <--RelatedTo--> Wet 