Boolean options available in all versions (with default values in []):

confirm		ask before hitting tame or peaceful monsters  [TRUE]
DECgraphics	use DEC/VT line-drawing characters for the dungeon [FALSE]
(fe)male	sex of the player (may only be set on startup)  [MALE]
fixinv		try to retain the same letter for the same object  [TRUE]
help		print all available info when using the / command [TRUE]
IBMgraphics	use IBM extended characters for the dungeon [FALSE]
ignintr		ignore interrupt signal, including breaks  [FALSE]
number_pad	use the number keys to move instead of yuhjklbn  [FALSE]
pickup		automatically pick up objects you move over  [TRUE]
rest_on_space	count the space bar as a rest character  [FALSE]
safe_pet	prevent you from (knowingly) attacking your pet(s)  [TRUE]
silent		don't use your terminal's bell sound  [TRUE]
sortpack	group similar kinds of objects in inventory  [TRUE]
time		display elapsed game time, in moves  [FALSE]
tombstone	print tombstone when you die  [TRUE]
verbose		print more commentary during the game  [TRUE]

There are further Boolean options that exist in some versions of NetHack 3.0.
(You can tell which options exist in your version by checking the short
option help, which is reached by 'O?'.)
 
Boolean option if NEWS was set at compile time:
news		print any news from game administrator on startup  [TRUE]

Boolean options if you are using MS-DOS and DGK was set at compile time:
IBM_BIOS	allow the use of IBM ROM BIOS calls  [FALSE]
rawio		allow the use of raw I/O (may only be set on startup)  [FALSE]

Boolean options if DGK was not set at compile time:
null		allow nulls to be sent to your terminal  [TRUE]
		try turning this option off (forcing NetHack to use its own
		delay code) if moving objects seem to teleport across rooms
standout	use standout mode for --More-- on messages  [FALSE]

Boolean option if TEXTCOLOR was set at compile time:
color		use different colors for objects on screen  [TRUE]

Any Boolean option can be negated by prefixing it with a '!' or 'no'.

 


 
Compound options are written as option_name:option_value.
Compound options which can be set during the game are:

packorder	a list of default symbols for kinds of objects that gives the
		order in which your pack will be displayed
		If you specify only some kinds of items, the others from the
		default order will be appended to the end.  [")[%?+!=/(*`0_]
endgame		the parts of the score list you wish to see when the game ends
		You choose a combination of top scores, scores around that of
		the ending game, and all of your own scores.
		[!own/3 top/2 around]
fruit		the name of a fruit you enjoy eating
		(basically a whimsy which NetHack uses from time to time)
		[slime mold]

Compound options which may be set only on startup are:

name		the name of your character
		[obtained by asking the system or the player]
dogname		the name of your first dog  [NONE]
catname		the name of your first cat  [NONE]
 
graphics	a list of symbols to be used in place of the default ones for
		drawing the dungeon
		The symbols are subjected to a fair amount of processing, so
		that you can use C-style escapes such as \n or \081 as well as
		indicate control characters by ^x or meta characters by \Mx.
		As usual, \ can force the next character to be taken literally.
		Since many of the default symbols are overloaded, they are
		given here by name instead of symbol, with some added notes.
		[stone                               (solid rock, normally ' ')
		vwall hwall tlcorn trcorn blcorn brcorn       (room boundaries)
		crwall tuwall tdwall tlwall trwall  (wallified maze characters)
		vbeam hbeam lslant rslant			    (zap beams)
		ndoor vodoor hodoor cdoor   (no, vert-open, horiz-open, closed)
		room corr upstair dnstair trap web pool
		fountain sink throne altar
		upladder dnladder vdbridge hdbridge]

Some sample options lists are
!pickup,!tombstone,name:Gandalf,endgame:own/3 top/2 around
female,nonews,dogname:Rover,graphics: |--------|||-\\/+.#<>\^\"}{#\\_<>##
rest_on_space,!verbose