Physical danger from the environment, especially with risk of drowning
An obstacle that hinders achievement of a goal.
The state of being difficult, or hard to do.
An objection.
An awkward situation or quarrel.
That which cannot be easily understood or believed.
no apology is necessary; think nothing of it (said in response to an expression of regret)
certainly, sure (said when granting a request)
no thanks is necessary; you're welcome (said in response to an expression of gratitude)
Something easy, not difficult, not posing problems.