Tack

As an object,
- A small sharp nail, such as one used to hook carpet in place.
- A rope used in sailing to change direction

As an action
- In sailing it means changing direction of the boat by tying the sail here and there, as needed.

Example
"I wished to reach you without loss of time, and I did what people will do in politics, or on the sea when the wind is against them, -- I tacked."
Johan de Witt to his brother Cornelius de Witt, in The Black Tulip by Dumas

Guerdon

Reward for an accomplishment or service.

John de Witt... too received a noble recompense for his devotedness to the best interests of his country, taking with him into the retirement of private life the hatred of a host of enemies, and the fresh scars of wounds inflicted by assassins, only too often the sole guerdon obtained by honest people, who are guilty of having worked for their country, and of having forgotten their own private interests.
from The Black Tulip, by Duma.

Mosey On

Walk slowly, as in leisure.

Example: There is one Calvin Hobbes strip with this word. Too good really.
Another, Lets mosey on home after dinner.

Boondocks

Rural place; more intense word than 'backwoods', or 'woods' or 'hinterland'.
The word comes from Philippino language, in which it means mountain. When American occupied the land towards the end of 19th century, they used this word to denote the mountainous hinterlands in Philippines.

Example
One of the few drawbacks to living out in the boondocks is that public services, such as litter collection, are less available than they are closer to the city.
Don't sweat the small stuff, by Richard Carlson

Au pair

A young foreigner who remains with a family as a surrogate family member, takes care of some of the house work such as baby-care etc. and in turn gets boarding, food and other amenities of being with a family, plus the learning of local language and culture.

Comes from the French au pair, meaning "on par" or "equal to". So the relationship with the person is on equal terms, he/ she is member of the family not a servant. Though the relationship is supposed to be temporary, its expected that they will remain in touch and on good terms years after the 'au pair' has left for his home country.

Example
One memory of that visit was of Jackie, the plump and pretty au pair at 18 Queens Road, who was huggable and on whom I had a crush.
Two Lives, by Vikram Seth