Adjust

#adjust is the extended command to change the letter that represents an item in your inventory.

Strategy
It is often useful to give commonly used items a letter that you can use each time you play the game. Here are some suggested letters for common items:

a - Primary Weapon - Your primary weapon always starts out being a. When you get a better primary weapon, adjust it to being "a" so you know it is now your primary one.

b - Secondary Weapon - Similar to using "a" as your primary weapon, most adventurers who start with a secondary weapon, will have it labeled b.

c - Primary Ranged Weapon - As an alternative, you might want to use "Q", which is the same letter as the command for placing an item in your quiver.

k - Key or Lock Pick - As an alternative use "K", because "k" is also the command for kick, and if the player mistypes applying a key, they may accidentally kick a door instead.

l - Lamp or Lantern

p - Pick Axe or other digging tool

u - Unicorn Horn

Y - Stethoscope - "Y" looks like the item in question.