noun:

• spine; line of the backbone
• seam down the back (of clothing)

noun:

• note; memorandum
• holding oneself back

godan ~る verb / intransitive verb:

• to withdraw; to leave
• to back down

expression / godan ~る verb:

• to perform anal sex; to bugger; to sodomize; to sodomise - colloquialism - vulgar ➜ お釜を掘る
• to crash one's car into the back of another

expression / godan ~る verb:

• to perform anal sex; to bugger; to sodomize; to sodomise ➜ 釜を掘る
• to crash a car into the back of another (usu. used in the passive voice); to rear-end

adverb:

• over the fence (e.g. looking, conducting a conversation)

~の noun:

• back-fence

noun:

• a month or older
• back numbers of a monthly

godan ~す verb / transitive:

• to wake up
• to bring back (e.g. memories); to recall

noun:

• hiding one's mistakes (or wrongdoings, etc.)
• back pocket

expression / godan ~す verb:

• to reply; to respond; to answer
• to talk back; to retort

noun:

• backwater ➜ バックウォーター
• standing with one's back to water (river, lake, etc.) - archaism

godan ~す verb / transitive:

• to reject; to repulse; to repel
• to bounce back; to counterattack; to strike back

expression / godan ~る verb:

• to follow suit; to imitate or follow someone blindly
• to ride on someone's back; to ride someone's coattails; to take advantage (e.g. of another's popularity)

noun:

• the heavenly eye - Buddhism term ➜ 五眼
• rolling back one's eyes during convulsions ［てんがん］ - obscure term

expression / ichidan verb:

• to take a solid stance
• to put one's back in it; to exert oneself ➜ 本腰を入れる

noun:

• essential part; indispensable part; unavoidable part; accompaniment; appendage; accessory
• front and back matter (of a book, magazine, etc.)

adverb / ~と adverb / ~する noun:

• rich (taste); full-bodied (flavour, flavor); mellow(ness) - onomatopoeia
• laid-back (lifestyle); relaxed; comfortable - onomatopoeia

noun:

• roof boards; ceiling
• back board (furniture)

noun:

• crying over spilt milk; complaining about things that have already happened - archaism
• speaking ill behind somebody's back; malicious gossip - archaism

noun:

• tea whisk; bamboo whisk for making Japanese tea
• hair style where the hair is tied up in a bundle on the back of the head (resembling the shape of a tea whisk)

ichidan verb / intransitive verb:

• to break; to be broken; to snap; to fracture
• to be folded
• to give in; to back down; to yield; to submit
• to turn (a corner) ➜ 曲がる

godan ~う verb / transitive:

• to finish; to stop; to end; to put an end to; to bring to a close
• to close (a business, etc.); to close down; to shut down; to shut up
• to put away; to put back; to keep; to store

auxiliary verb / godan ~う verb:

• to finish ...; to do ... completely - after the -te form of a verb, indicates completion (and sometimes reluctance, regret, etc.)

noun:

• portable shrine (carried in festivals) - polite language ➜ 御輿
• buttocks; lower back; waist; hips - usually written using kana alone ➜ 腰【こし】

adverb / ~と adverb / ~する noun:

• relieved; refreshed - onomatopoeia
• easy-going; laid-back; frank; candid - onomatopoeia

ichidan verb / transitive:

• to hang; to suspend; to wear (e.g. decoration)
• to lower; to reduce; to bring down
• to demote; to move back; to pull back
• to clear (plates); to remove (food, etc. from table or altar)