Command-line word lookup based on Apple's built-in dictionaries

dict.swift

import Foundation
import CoreServices

if CommandLine.argc < 2 { exit(1) }
let word = CommandLine.arguments[1] as CFString
let rang = CFRangeMake(0, CFStringGetLength(word)) //DCSGetTermRangeInString(nil, word, 0)
let defn = DCSCopyTextDefinition(nil, word, rang)
if defn != nil { print(defn!.takeUnretainedValue() as String) }