skid lid vs crash helmet

skid lid and crash helmet both are nouns.

Word	Noun	Adjective	Verb	Adverb
skid lid	Yes	No	No	No
crash helmet	Yes	No	No	No

As nouns, crash helmet is a hypernym of skid lid; that is, crash helmet is a word with a broader meaning than skid lid:

skid lid: a crash helmet
crash helmet: a padded helmet worn by people riding bicycles or motorcycles; protects the head in case of accidents

skid lid (noun)	crash helmet (noun)
a crash helmet	a padded helmet worn by people riding bicycles or motorcycles; protects the head in case of accidents