smooth
Soft
mushy
Soft
compassionate, cushioned, squishy
Microsoft is the name of a company; it has no synonym. A synonym for each of its parts would be: Micro-small, soft-tender, gentle.
soft, feeble, weak, flabby
obedient, resigned, gentle, soft, cool
It depends on the use of the word "soft". In the sentence "the pillow was so soft" it has a different meaning to "quiet" With the sentence "Her voice was so soft" then "soft" can be a synonym of "quiet" But, someone who is softly spoken is not always quietly spoken. A soft voice can also mean "soothing" or "calm". Even when "soft" is used to describe sound, it does not always mean exactly the same as "quiet"
comfortable, soft, intimate, secure, safe, sheltered, warm
careful, tender, kind, soft, mild, gingerly
If you mean hard as in the opposite of soft, then rigid, firm, adamatine. If you mean the opposite of easy, then difficult
A synonym for cushion is a pillow because they are both soft. pad, bolster, headrest, beanbag, hassock