flag, meadow

Concise Bible Dictionary:

1. achu, a soft reed that can only grow in moist ground: it is eaten by cattle (Job 8:1111Can the rush grow up without mire? can the flag grow without water? (Job 8:11)).
Cyperus Papyrus—Reeds that Grow Along the Nile
Cyperus Papyrus

Strong’s Dictionary of Hebrew Words:

Transliteration:
’achuw
Phonic:
aw’-khoo
Meaning:
of uncertain (perhaps Egyptian) derivation; a bulrush or any marshy grass (particularly that along the Nile)
KJV Usage:
flag, meadow