The path is incomplete in your file. You missed out some numbers… and you maybe mistyped the ID “thermometer-3”. Here below is a working file incl. the ACCOUNT SVG from www.materialdesignicons.com
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" id="Layer_1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" x="0px" y="0px"
viewBox="0 0 48 48" enable-background="new 0 0 48 48" xml:space="preserve">
<symbol id="thermometer-3">
<g>
<path d="M17,17A5,5 0 0,1 12,22A5,5 0 0,1 7,17C7,15.36 7.79,13.91 9,13V5A3,3 0 0,1 12,2A3,3 0 0,1 15,5V13C16.21,13.91 17,15.36 17,17M11,8V14.17C9.83,14.58 9,15.69 9,17A3,3 0 0,0 12,20A3,3 0 0,0 15,17C15,15.69 14.17,14.58 13,14.17V8H11Z" >
</path>
</g>
</symbol>
<symbol id="account">
<g>
<path d="M12,4A4,4 0 0,1 16,8A4,4 0 0,1 12,12A4,4 0 0,1 8,8A4,4 0 0,1 12,4M12,14C16.42,14 20,15.79 20,18V20H4V18C4,15.79 7.58,14 12,14Z" >
</path>
</g>
</symbol>
</svg>