Synonyms for Understanding:

adj.

accepting, tolerant (adjective)
compassionate, generous, perceptive, sympathetic, responsive, kindly, forbearing, empathetic, patient, forgiving, discerning.
agreeable (adjective)
consensual, compatible, congenial, Capitulating, agreeable, friendly, concordant, likeable, willing, co-operative, pleasant, empathetic, assenting, acquiescent, amiable, harmonious.
intellectual (adjective)
rational, cerebral, intelligent, egghead, psychological, reasoning, intellectual, brainy, thinking.
responsive (adjective)
sympathetic, responsive, compassionate.

n.

common ground, alliance. lore, experience, grip, expertise, hold, sensitivity, grasp, awareness, Familiarity. smart, brainpower, common sense, brilliance, intuition, vision, clarity, ability, wit. pity, agree, compassion, bargain, humanity, sentiment, commiseration, affinity, condolences. magnanimous, empathic, forgiving, feeling, indulgent, merciful, forbearing, clement, understand. connotation, patient, thrust, subtext, usage, significance, kindly, generous, substance, meaning, denotation. agreement (noun)
compact, capitulation, concurrence, accordance, accord, bond, empathy, acceptance, contract, concord, treaty, pledge, settlement, pact, unanimity, accession, arrangement, agreement, concordance, deal, assent, acquiescence, stipulation, covenant, consensus, consent, promise.
belief (noun)
sympathy, significance, meaning.
comprehension, appreciation (noun)
awareness, discernment, intuition, grasp, apprehension, knowing, knowledge, reason, savvy, intellect, ken, grip, wit, intelligence.
concurrence (noun)
agreement.
empathetic (noun)
empathic, patient, generous, kindly.
feeling (noun)
empathy.
informal agreement (noun)
accord, pact, concord, deal.
intellect (noun)
capacity, cerebration, mind, comprehension, brain, reason, reasoning, thinking, thought, intelligence, rationality, intellect, brain-power, mentality.
intelligence (noun)
mind, brainpower.
knowledge (noun)
information, cognizance, ken, erudition, know-how, knowledge, wisdom, education.
knowledgeableness (noun)
Familiarity.
meaning (noun)
significance.
obligation (noun)
obligation.
promise (noun)
guarantee, assurance, oath, mutual agreement, engagement, obligation, vow.
savvy (noun)
savvy.
sense (noun)
rationality.
thought (noun)
thought, thinking.
understanding (noun)
intellect, agreement, perceptive, discernment, reason, savvy, sympathy, apprehension.

v.

believing (verb)
judging, gathering, holding, assenting, concluding, Affirming, professing, taking for granted, Presuming, Surmising, Crediting, believing, Supposing, giving faith, Maintaining, assuming, Deeming, Declaring, trusting, putting faith in, accepting.
knowing (verb)
discerning, Recognizing, knowing, Perceiving.
learning (verb)
mastering, grasping, studying, learning, Digesting, absorbing, Realizing, reading, assimilating, Discovering, Gleaning, Comprehending.

Other synonyms:

common ground, brainpower, expertise, ability, lore, empathic, commiseration, awareness, forgiving, alliance, Familiarity, experience, compassion, magnanimous, pity. sensitivity, sentiment, clement, humanity, affinity, merciful. bargain. wit. grip. Other relevant words:
empathic, apprehension, grasp, discernment, sensitivity, sympathy, wit, awareness.

Usage examples for understanding

  1. If he did so, the young man was determined that he should have an understanding with him. – The Firm of Girdlestone by Arthur Conan Doyle
  2. Again, hardly understanding why, Steve flushed. – Man to Man by Jackson Gregory
  3. Gilbert said, not understanding – The Bad Man by Charles Hanson Towne