So, full and half positions are common terminology in the stock market world, especially for those who are looking to dollar cost average, which means to buy in gradually over time.
Say you have a stock you want to buy. You have a $100,000 portfolio and you want this stock to make up $5000 of it.
If someone were to say they purchased a full position, that means they simply took $5000 and purchased the stock. They will no longer look to add more, except maybe when they rebalance.
If they took a half position, that means they purchased $2500 of it, with the plan to purchase another $2500 in the future to "complete" their position.
There is two reasons why someone would take a half position. One being they want to reduce overall market volatility and the risk of purchasing something in full, and then it falling in price. So they say I'll purchase $XX amount now, and $XX amount a month from now.
Or, they simply are 100% invested at all times, and use cash flow into the account to buy in increments. For example, say your portfolio is $95,000 and you want to own a 5% total allocation to a particular stock. But, your $95,000 is currently invested. You plan to add $1000 a month to the account. Over the course of 5 months, you could purchase $1000 a month of the stock and average in over the course of those 5 months.
Does this make sense? Full position is buying all at once. Half position would be half now, half at a pre-determined time in the future. But, you can also extend it out like I said to 1/4, 1/5 etc.