December has always been a good month for a party. With the Romans it was endless feasting and frolic for the seven days of Saturnalia, while we moderns have chosen to spread out our merrymaking from Thanksgiving to New Year's.

(The Puritans, you will be sorry to know, broke with tradition, declaring by an Act of Parliament in 1644 that all such celebrations were pagan and therefore forbidden.)

If there is ever a time when you will be called upon to lift a cup of cheer, it is December, and to make sure that cups runneth over, it is necessary to take stock of the liquor cabinet.

From Central Liquors, 518 9th St. NW, come suggestions for the basic holiday bar:

Buying their lowest priced house brands, you would pay $3.99 a fifth for Scotch ($8.77 for 1.75 liters, or approximately a half gallon; all prices in parenthesis are for the larger size); vodka, $3.79 a fifth ($5.89); bourbon, $3.79 a fifth ($8.17); gin, $3.99 a fifth ($6.19); brandy, $3.99 ($9.79). The well-stocked bar would also have vermouth (a small-sized bottle of either sweet or dry is $1.69) and wine. Central recommends Francia or BellaVina at $3.99 for four liters.

Now, having saved all this money on house brands, you can splurge on a little holiday glitter. For special celebrations when money is no object, or for small parties with a few close friends, Elliott Staren at MacArthur Liquors, 4877 MacArthur Blvd. NW, suggests some stars for the bar.

Among the sweeter liqueurs are the orange-flavored Grand Marnier, $17.99, and Bailey's Irish Cream, $13.99. For a very special cognac, he recommends Frank Schoonmaker's Reserve Special, for $29.99, or a pear brandy, Danflou's Poire Williams at $33.99, or Massenex framboise, $25.99, a brandy distilled from raspberries which is particularly good served chilled with chocolate desserts.

For a sherry, there is Avery's Amontillado Pasda for $7.49 and for port, Dow's 1969 Reserve at $8.99. (Stilton cheese, hollowed a bit at the center and filled with enough port to seep into the cheese, makes a wonderful holiday cheese course.)

If you take your rum neat, Staren suggests Mount Gay Eclipse at $7.99. When it will be merged into an eggnog or toddy, buy the less expensive Bacardi at $5.79. His suggestion for wine would be Cuvee du Baron, red or white, $5.69 the magnum or $31.89 the case.

The well-equipped bar should also have a jigger, a corkscrew, a bottle opener, ice, soda, tonic, beer and soft drinks, a cocktail shaker or pitcher and a good recipe book for cocktails if you're a novice. It's also a good idea to check the refrigerator for lemons, olives and cocktail onions and to have on hand a supply of sugar syrup for the holiday grogs and toddies:

Boil one part water to two parts sugar for five minutes. Keep the syrup refrigerated until needed.

And, of course, coffee, tea and milk for those who don't drink.