紙上談兵 [纸－谈－]

Jyutping zi2 soeng6 taam4 bing1
Pinyin zhǐ shàng tán bīng

Definitions (CC-CEDICT)
  1. lit. military tactics on paper (idiom)
  2. fig. theoretical discussion that is worse than useless in practice
  3. armchair strategist
  4. idle theorizing
  5. cf Zhao Kuo 趙括|赵括[Zhao4 Kuo4] leading an army of 400,000 to total annihilation at battle of Changping 長平之戰|长平之战[Chang2 ping2 zhi1 Zhan4] in 260 BC
Definitions (粵典–words.hk)
  1. 語句
    得個​講字​，​冇​任何​實際​行動
    to be an armchair strategist; to engage in idle theorizing; literally: to talk about stratagems only on paper
    • 佢淨係識紙上談兵，我從未見過佢親自落場！
      佢净系识纸上谈兵，我从未见过佢亲自落场！
      He only knows how to theorizing, I have never seen him in the field.
Definitions (Wiktionary)
  1. phrase, idiomatic
    to engage in theoretical discussion that is worse than useless in practice; armchair strategist; idle theorizing
Examples (粵典–words.hk)
  1. Cantonese
    佢净系识纸上谈兵，我从未见过佢亲自落场！
    佢淨係識紙上談兵，我從未見過佢親自落場！
    • He only knows how to theorizing, I have never seen him in the field.