Definition (full): fat, fatness, a rich dish, a fertile field, a robust man
Strong's Exhaustive Concordance
From shaman; fat, i.e. (literally and abstractly) fatness; but usually (figuratively and concretely) a rich dish, a fertile field, a robust man -- fat (one, -ness, -test, -test place).
KJV: Then he said unto them, Go your way, eat the fat, and drink the sweet, and send portions unto them for whom nothing is prepared: for this day is holy unto our Lord: neither be ye sorry; for the joy of the LORD is your strength.
NASB: Then he said to them, "Go, eat of the fat, drink of the sweet, and send portions to him who has nothing prepared; for this day is holy to our Lord. Do not be grieved, for the joy of the LORD is your strength."
KJV: Therefore shall the Lord, the Lord of hosts, send among his fat ones leanness; and under his glory he shall kindle a burning like the burning of a fire.
NASB: Therefore the Lord, the GOD of hosts, will send a wasting disease among his stout warriors; And under his glory a fire will be kindled like a burning flame.
KJV: He shall enter peaceably even upon the fattest places of the province; and he shall do that which his fathers have not done, nor his fathers' fathers; he shall scatter among them the prey, and spoil, and riches: yea, and he shall forecast his devices against the strong holds, even for a time.
NASB: "In a time of tranquility he will enter the richest parts of the realm, and he will accomplish what his fathers never did, nor his ancestors; he will distribute plunder, booty and possessions among them, and he will devise his schemes against strongholds, but only for a time.