1. impinge = strike
The word impinge can have various meanings, but in the case above, it means to strike. When 'the rain impinge[d] upon the earth,' it means that it started raining, the rain started striking the earth. To impinge means that something starts, and usually something negative.
2. garrulous = loquacious
The word garrulous refers to someone who talks excessively, likes to talk a bit too much, and usually about something trivial. Loquacious is a fancy word to denote the same thing, although it has a more positive connotation - it refers to someone who can speak nicely.
3. pious = religious
The word pious comes from the Latin word pius, which means dutiful. So when English took this word from Latin, it added a different suffix (-ous), and gave it the meaning of being 'dutiful to God.' So nowadays, pious refers to someone who is devoutly religious.
4. ruinous = dilapidated
The word ruinous refers to something which is in ruins, which is falling apart. The word which means the same thing is dilapidated - both of these words are usually used to describe buildings that are very old, and derelict, and are practically in ruins.
Puns were used by Shakespeare to explain meaning, to make sense of the world around his characters. If a certain scene in his play was a bit confusing, he would often use a pun, which is a play on words, in order to explain what is happening in more detail. His puns were very clever, and many of them are still used today, without people even realizing how old they actually are.
Susie's mom bought her SOMETHING at the grocery store.
Vague nouns are unspecific things that don't tell you exactly what something is!
More examples of vague nouns: something, things, stuff, etc.
