difficult to ... (physically or emotionally); hard to ...
behavior; behaviour; manner; attitude; bearing
cleaning; sweeping; dusting; scrubbing
washing; laundry; relaxation; rejuvenation; melting away (of worries, fatigue, etc.)
strict; severe; stern; rigid; rigorous; tough
mental preparedness; being braced for; being steeled for
to become loose; to slacken (e.g. rope); to become less tense; to relax; to slacken (e.g. coldness, supervision); to become lax; to become softer (e.g. ground, facial expression)
severe; strict; hard (to do); difficult; intense (e.g. cold); harsh (weather)
to put back; to return; to vomit; to throw up; to recover (of a market price)
power; might; authority; influence
control (of a machine, device, etc.); control (over an opponent, one's emotions, etc.); governing; management
strength; power; proficiency; ability
element; component; factor; element (e.g. in array); member (e.g. data structure)
not exceeding ...; not more than ...; below (a standard, level, etc.); under; the following; the below-mentioned
dated; date; date of effect (e.g. a rule change); fixed; external
item; heading; category; headword (in a dictionary, encyclopedia, etc.); entry
possibility; chance; potential; potentiality; possibility (modal property of a proposition containing no logical contradiction)
discouraged; dispirited; despondent
term; terminology; wording; choice of words; phraseology
mouthful; morsel; gulp; sip; one word; in short
continuously; the whole time; much (more); (by) far; far (away); long (ago, before, after)
use; exercise (of one's right, authority, power, etc.)
obsession; fixation; complaining; criticizing; speciality (e.g. of a restaurant)
best; supreme; wonderful; highest; maximum; most
person; -er; (arch.) expert; (arch.) geisha; (arch.) prostitute
necessary; needed; essential; necessity; need; requirement
to respond; to answer; to meet (e.g. demands, expectations); to affect; to take a toll; to strike home
the best one can do; one's best effort; with all one's might; to the best of one's ability; as hard as possible
plot of land; lot; soil; locality; region; place
to become thin; to lose weight; to slim; to become impoverished (of soil); to become sterile; to become infertile
theory; doctrine; opinion; view; rumour; rumor
surrounding countries; neighboring countries; neighbouring countries
quite; very; 10^48; quindecillion
revelation; manifestation; appearance; expression (e.g. in molecular biology; protein expression or gene expression)
everyone; everybody; all; everything; all
head; hair (on one's head); mind; brains; leader; chief; top