台 tái = term of address? Is this address?
When 台 means 'platform', you may see it in 月台 (train platform), 舞台 (stage), 電台 (radio station), 電視台 (TV station) etc.

When 台 is a unit, you may see it in 一台貨車 (a truck), 一台電腦 (a computer); it is a counter for bulky objects.

台 may also be an abbreviation for Taiwan, as in 台式 (Taiwanese style).

台 as a term of address (address here means speaking or writing to someone, not a location) is possible, although somewhat archaic / formal. In the past it is very common to attach ～鑒 after the addressee's name in letters. Depending on their status relative to yours, you choose the correct character before 鑒: e.g., 台鑒 for peers, 鈞鑒 for reverent people, and 雅鑒 for ladies. You also end the letter with salutations like 即候台安 or 順頌台祺, again depending on your status. Put simply, 台 is a general term of address for peers. If you're interested you may refer to this link to see an exhaustive list on the correct terms of address in various situations.