Slip of the tongue ( বলায় সামান্য ভুল ) This is a slip of the tongue, don't lay much stress on it.
At home ( দক্ষ ) He is at home in mathematics.
A blessing in disguise ( বিপরীতে হিত ; প্রথমে খারাপ হিসেবে মনে হলেও পরবর্তীতে ভালো হয় ) Sam's motorcycle accident was a blessing in disguise because he got enough insurance money.
Part and parcel ( অবিচ্ছেদ্য অংশ ) Discipline is part and parcel of administration.
On the whole ( মোটের উপর ) On the whole, his conduct is good.