1. Pachyderm . Definition: a thick-skinned animal, especially an elephant or a rhinoceros. It is derived from the Greek word for thick-skinned and dates from 1838.

When was it used? -- Joni Mitchell sang "I know you've got all those girls coming on/hanging on your boom-boom-pachyderm" on her 1976 song "Blue Motel Room." Based on the dictionary definition of pachyderm, I have no idea what the lyric means. Hanging on your thumpin' rhino? Frankly it sounds kind of dirty, in a "Tusk" sort of way (see Mac, Fleetwood, 1979).

What rhymes with it? -- Mitchell used "germs," avoiding the complications of rhyming beyond the last syllable; "tell them you got germs," she sings. I think "manicure" would work, or the simpler rhymes of "learn," "squirm," "firm," and "worm." Given these choices, "tell them you got worms" would have packed the most punch.

Use it in a sentence -- My pachyderm must be asleep or something.

2. Quisling. Definition: a traitor, especially one who collaborates with an enemy occupying their country. The word comes from V. Quisling, who sold out Norway to the Nazis in WWII.

When was it used? -- Elvis Costello saw the word on a sign in Madison, Wisconsin while on tour. He then used it on "Green Shirt" (1979); " ‘cause somewhere in the quisling clinic/ there's a shorthand typist taking seconds over minutes." For a guy who wanted to title the album Emotional Fascism and had a song on it called "Two Little Hitlers," the word's Nazi origin makes it an appropriate fit.

What rhymes with it? -- Whistling, kissing, missing, etc. The word wasn't used at the end of a line in the song, so no rhyme was necessary.

Use it in a sentence -- The president told Elvis to search out the quislings.

3. Effloresce and Deliquesce. Definition of effloresce: to burst out into flower. Definition of deliquesce: to become liquid, to melt.

When was it used? -- "Effloresce and Deliquesce" is the title of a 1991 song by the Chills, and the phrase is used five times in the lyrics. The song is about love gone sour, hence the flowering that melts away.

What rhymes with it? -- "Effervesce" apparently (definition: to give off small bubbles of gas), as it is brought in for the rhyme in the first verse. Other rhymes in the song include "regrets," "rest," and "best." If only the last syllable is used, the rhyming possibilities seem endless: "jest," "duress," "dress," "crest," "impress," "bereft," "success," "confess," I could go on and on. Another possibility would have been to ditch effloresce and deliquesce altogether, and instead called the song "Blossom and Fade." I can think of just as many rhymes for "fade," and so can you.

Use both words in the same sentence -- The bloom is off the rose.

4. Topiary. Definition: The art of clipping shrubs and trees into ornamental shapes. This was what the lead character in the movie Edward Scissorhands did in his spare time.

When was it used? -- In his 1994 song "N.Y.C." Bryan Ferry sings, "house and garden topiary."

What rhymes with it? -- Possibly "apiary" (definition: a hive where bees are kept), or the phrase "quite contrary," but not much else, though it does rhyme with "Ferry," who didn't bother to rhyme it with anything.

Use it in a sentence -- She spent five years working on a Bryan Ferry topiary and it still wasn't any good.

5. . Terrarium. Definitions: 1. A sealed transparent globe containing growing plants; 2. A place where land animals are kept in an approximate natural state for observation.

When was it used? -- Pavement's 1997 song "Type Slowly" has a lyric that goes, "not a lot of room to grow inside this leather terrarium."

What rhymes with it? -- "Solarium," "aquarium," "sanitarium," which all come from the same Latin word meaning a place where live things are kept. In the song Malkmus sort of rhymed it with "creation."

Use it in a sentence - I put Stephen Malkmus in a terrarium just to watch him obfuscate.