Dictionary:

algarroba

  (ăl'gə-rō'bə)

1. 1. See mesquite (sense 1).
   2. The edible pod of this plant.
2. See carob (sense 1).

[American Spanish, mesquite, from Spanish, carob, from Arabic al-harrūba : al-, the + harrūba, carob pod (from harrūb, carob).]

The noun has 4 meanings:

Meaning #1: long pod containing small beans and sweetish edible pulp; used as animal feed and source of a chocolate substitute
  Synonyms: carob, carob bean, algarroba bean, locust bean, locust pod

Meaning #2: evergreen Mediterranean tree with edible pods; the biblical carob
  Synonyms: carob, carob tree, carob bean tree, Ceratonia siliqua

Meaning #3: mesquite pod used in tanning and dying
  Synonyms: algarrobilla, algarobilla

Meaning #4: mesquite of Gulf Coast and Caribbean islands from Mexico to Venezuela
  Synonyms: Prosopis juliflora, Prosopis juliiflora