A shorted share or short selling share is an type of bet where you are expecting a certain stock/security to fall in price. Example: Suppose you think that the stock ABC is overpriced and will decrease its price in the near future. So, you can “borrow” shares from a broker and not pay them immediately, you pay them back after, say, 1 month. Suppose the current price of the shares are $10 per share, and you borrowed 100 shares and you immediately sell them in the market for $10 * 100 = $1,000. Then, after a month, the prices fell to $8 per share, and now you pay back the broker not at the previous $10 per share, but the current $8 per share. Hence, you pay the broker $800 for the 100 shares you borrowed, and thus you profit $1,000 - $800 = $200 or $2 per share.
However, if your prediction is wrong and the price does not fall, rather it rises, then you will have to pay the broker more and thus you lose money.
SHARES_SHORT is the total number of shares that were shorted last month. For example. SHARES_SHORT for AAPL currently is over 123 million.
Shares Short Prior Month
SHARES_SHORT_PRIOR_MONTH is the total number of shares that were shorted the month before last month. Example: AAPL has SHARES_SHORT_PRIOR_MONTH of over 82 million shares.
Shares Percent of Float
SHORT_PERCENT_OF_FLOAT is the percentage of the total float shares that were shorted last month. Note: Current float may be different. For instance, AAPL's SHORT_PERCENT_OF_FLOAT is 0.0074% currently.
SHORT_RATIO is the number of shares shorted last month divided by average daily volume since inception. Example: SHORT_RATIO is the 1.36 for AAPL.