Participial Adjective (Verbal Adjective)

 A participial adjective is an adjective coincident with the-ing form or -en form of the verb to which it is related (Oxford Dictionary of English Grammar)

Her story was very frightening.     -present participle adjective

He seems very worried

The vase is broken                         -past participle adjective

The shop is closed at five o'clock  -past participle (verb)/passive voice

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-ed form    alarmed, amazed, bored, excited, frightened, pleased, surprised, tired, worried, delighted, renowned, self-centered

-ing form   alarming, amazing, boring, exiting, frightening, pleasing, surprising, tiring, worrying, welcoming

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Modified by adverbs ---very alarming, most alarmed

If participle adjective has both -ing form and -ed form, the the-ing form describes something (the exciting/thrilling movie) and -ed form describes someone (annoyed/bored/disgusted person)

The movie was frightening

The frightened children shouted for help

Sometimes it becomes difficult to separate the verbal and adjectival use of participle. In these cases, you should apply the very test. If the very test applies, then it is adjectival, otherwise it is verbal. 

a. I was disappointed to hear the news  (adjectival, because we can say very disappointed)

b. I was disappointed by the news  (verbal, because we cannot say very disappointed)

Compare a sleeping child with a horrifying story. We shall consider it to be a participial modifier. If it can be graded or intensified by very, we consider it an adjective. 

1. (participial modifier)    sleeping child       not *a more/very sleeping child

2. (adjective)       a more/very horrifying story      the story is more/very horrifying

Furthermore, is sleeping in the child is sleeping will be interpreted as a verb, the predicative adjective being asleep. 

In examples such as sleeping bag, sleeping pill, the word sleeping is neither adjective nor verb, but a noun modifier (a bag/pill for sleeping), the combination now having the status of a count noun.

Past participles may often have either an adjectival or verbal interpretation. In The flat was furnished, the participle may be understood either as part of passive verb form or as the adjectival Cs of the copula was.

COMPOUND FORMS

Many participial forms are compounded with a noun, an adjective or an adverbial prefix whose syntactic relationship with the verbal participle may be Subject, Object or Adjunct. 

-ing : heart-breaking news; good-looking girl; fast-selling magazines

-en  : well-paid workers; sun-tanned legs; well-known brands

Reference :

Chalker, S, Weiner, E. 1994. Oxford Dictionary of English Grammar. New York : Oxford University Press Inc. 

Cowan, Ron. 2008.The Teacher's Grammar of English. New York : Cambridge University Press 

Downing, A., Locke, P.  English Grammar A University Course Second Edition. 2006. New York : Routledge

Gupta, S.M., 2019. Current English Grammar and Use Second Edition. Delhi : PHI Learning Private Ltd. 

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